Exhibit 99.1

FOR IMMEDIATE RELEASE

DATE: January 29, 2014

HERITAGE FINANCIAL ANNOUNCES FOURTH

QUARTER AND ANNUAL RESULTS AND DECLARES

REGULAR CASH DIVIDEND

Olympia, WA—HERITAGE FINANCIAL CORPORATION (NASDAQ GS: HFWA) Brian L. Vance, President and CEO of Heritage Financial Corporation (“Company” or “Heritage”), today reported that the Company had net income of $710,000 for the quarter ended December 31, 2013 compared to net income of $3.0 million for the quarter ended December 31, 2012 and $3.3 million for the linked-quarter ended September 30, 2013. Net income for the quarter ended December 31, 2013 was $0.04 per diluted common share compared to $0.20 per diluted common share for the quarter ended December 31, 2012 and for the linked-quarter ended September 30, 2013.

Net income for the year ended December 31, 2013 was $9.6 million, or $0.61 per diluted common share, compared to $13.3 million, or $0.87 per diluted common share, for the year ended December 31, 2012.

Mr. Vance commented, “2013 was a transitional year for the company. In addition to completing two acquisitions, we also completed the merger of our Central Valley Bank subsidiary into Heritage Bank and we signed a definitive agreement with Washington Banking Company to enter into a strategic alliance that will extend the reach of Heritage Bank from the Canadian border south to Portland, Oregon. During the fourth quarter we reduced our branches from 42 to 35 and we reduced full-time equivalent employees from 415 to 373.” Mr. Vance continued, “The costs associated with these initiatives negatively impacted our fourth quarter after-tax earnings by approximately $2.4 million, or $0.15 per share. However, we expect these initiatives to have a significant positive impact on our future operating results.”

Acquisition of Northwest Commercial Bank

On January 9, 2013, the Company acquired Northwest Commercial Bank (“NCB”) and merged it into Heritage Bank (the “NCB Acquisition”). NCB was a full service commercial bank with branches in Lakewood and Auburn, Washington. In March 2013, the Company consolidated the operations of the former NCB Lakewood branch with the Lakewood branch of Heritage Bank.

The Company paid cash consideration of $3.0 million, or $5.50 per share, to the NCB shareholders. Additionally, as provided for in the merger agreement, NCB shareholders had the ability to potentially receive an additional cash payment based on an earn-out structure from the sale of an “other real estate owned” asset of NCB. This contingent payment was included in the NCB liabilities assumed as of the January 9, 2013 acquisition date. During the quarter ended June 30, 2013 this asset was sold and the $491,000 in proceeds from the sale was paid to the former NCB shareholders during the quarter ended September 30, 2013. This payment did not impact the recorded bargain purchase gain on bank acquisition of $399,000.

In connection with the NCB Acquisition, the Company received (at fair value) approximately $51.5 million in loans, $2.7 million of cash and cash equivalents, $2.8 million in investment securities, $2.9 million in net deferred tax assets, $2.3 million in other real estate owned, $1.0 million of other interest earning deposits and $1.9 million in other assets. The Company also assumed deposits with a fair value of approximately $60.4 million and $1.2 million of other liabilities. The application of the acquisition method of accounting resulted in the recognition of a pre-tax bargain purchase gain on bank acquisition of $399,000. The bargain purchase gain on bank acquisition represents the excess of the estimated fair value of the net assets acquired and the liabilities assumed over the purchase price.

Central Valley Bank Merger

On June 19, 2013, the Company completed the merger of its subsidiary, Central Valley Bank (“CVB”), with and into Heritage Bank (the “CVB Merger”). CVB is now operated as a division of Heritage Bank.

Acquisition of Valley Community Bancshares

On July 15, 2013, the Company completed the acquisition of Valley Community Bancshares, Inc. (“Valley”), the holding company for Valley Bank, both of Puyallup, Washington (the “Valley Acquisition”). Pursuant to the terms of the merger agreement, Valley shareholders received for each share of Valley common stock $19.50 in cash and 1.3611 shares of Heritage common stock. As of the acquisition date, Valley merged into Heritage and Valley Bank merged into Heritage Bank.

In connection with the Valley Acquisition, the Company received (at fair value) approximately $117.1 million in loans, $40.6 million of cash and cash equivalents, $13.9 million of other interest earning deposits, $54.4 million in investment securities, $6.6 million in premises and equipment, $916,000 in core deposit intangible and $3.9 million in other assets. The Company also assumed deposits with a fair value of approximately $207.0 million and $342,000 of other liabilities. The application of the acquisition method of accounting resulted in the recognition of goodwill of $16.4 million. The goodwill represents the excess of the consideration transferred over the estimated fair value of the net assets acquired and the liabilities assumed.

Proposed Merger with Washington Banking Company

On October 23, 2013, the Company and Washington Banking Company (“Washington Banking”) jointly announced the signing of a definitive agreement under which Heritage and Washington Banking will enter into a strategic merger to create one banking franchise. Washington Banking branches will adopt the Heritage Bank name in all markets, with the exception of six branches in Whidbey Island markets which will continue to operate using the Whidbey Island Bank name. The corporate headquarters of the combined company will be in Olympia, Washington.

Under the terms of the merger agreement, Washington Banking shareholders will receive 0.89000 shares of Heritage common stock and $2.75 in cash for each share of Washington Banking common stock. Upon consummation, the shareholders of Washington Banking will own approximately 46% of the combined company and the shareholders of Heritage will own approximately 54%.

Balance Sheet

The Company’s total assets decreased slightly to $1.66 billion at December 31, 2013 from $1.67 billion at September 30, 2013.

Total originated loans receivable increased $15.4 million, or 1.6%, to $977.3 million at December 31, 2013 from $961.9 million at September 30, 2013. The increase from the prior period was due primarily to increases in owner-occupied commercial real estate loans ($13.9 million), non-owner occupied commercial real estate loans ($7.1 million) and construction loans relating to five or more family residential and commercial properties ($6.5 million) partially offset by a decrease of $9.8 million in commercial and industrial loans. The decrease in commercial and industrial loans was primarily due to a seasonal decline of $10.5 million in agricultural loans. Total originated loans receivable increased year-over-year by $102.8 million, or 11.8%, from $874.5 million at December 31, 2012.

Total deposits decreased $26.8 million, or 1.9%, to $1.40 billion at December 31, 2013 from $1.43 billion at September 30, 2013. Non-maturity deposits to total deposits were 77.9% at December 31, 2013 compared to 77.6% at September 30, 2013. In addition, noninterest demand deposits to total deposits were 25.0% at December 31, 2013 compared to 25.4% at September 30, 2013.

Total stockholders’ equity decreased to $215.8 million at December 31, 2013 from $216.6 million at September 30, 2013. The decrease during the three months ended December 31, 2013 was primarily due to cash dividends of $1.3 million and an increase of $480,000 in accumulated other comprehensive loss, net, partially offset by $710,000 in net income and $229,000 in stock-based compensation. The Company’s ratio of tangible common equity to tangible assets was increased slightly to 11.4% at December 31, 2013 compared to 11.3% at September 30, 2013. The Company and Heritage Bank continue to maintain capital levels significantly in excess of the applicable regulatory requirements for them to be categorized as “well-capitalized”. The Company had Tier 1 leverage, Tier 1 risk-based and total risk-based capital ratios at December 31, 2013 of 11.3%, 15.5% and 16.8%, respectively, compared to 11.6%, 15.5%, and 16.7%, at September 30, 2013, respectively.

Credit Quality

The allowance for loan losses on originated loans decreased $204,000, or 1.2%, to $17.2 million at December 31, 2013 from $17.4 million at September 30, 2013 as a result of $104,000 in net charge-offs recognized during the quarter ended December 31, 2013 and a provision for loan losses of $(100,000). Nonperforming originated loans to total originated loans decreased to 0.53% at December 31, 2013 from 0.81% at September 30, 2013. Nonaccrual originated loans decreased $2.8 million to $6.9 million ($5.2 million net of government agency guarantees) at December 31, 2013 from $9.8 million ($7.9 million net of government agency guarantees) at September 30, 2013. The decrease in nonaccrual originated loans was due to a $2.4 million loan restored to accrual status, $1.5 million of net principal reductions, $225,000 in transfers to other real estate owned and $58,000 of charge-offs partially offset by an addition of $1.4 million in loans to nonaccrual originated loans.

The allowance for loan losses to nonperforming originated loans was 329.40% at December 31, 2013 compared to 221.68% at September 30, 2013. Potential problem originated loans increased to $30.1 million at December 31, 2013 from $26.6 million at September 30, 2013 primarily as a result of a $3.3 million loan that was downgraded to special mention status during the quarter ended December 31, 2013. Restructured originated performing loans increased to $20.4 million at December 31, 2013 compared to $19.6 million at September 30, 2013. The Company believes that its allowance for loan losses is appropriate to provide for probable incurred losses based on an evaluation of known and inherent risks in the loan portfolio at December 31, 2013.

Nonperforming originated assets were $11.3 million ($9.6 million net of government agency guarantees), or 0.68% of total originated assets, at December 31, 2013, compared to $13.6 million ($11.7 million net of government agency guarantees), or 0.83% of total originated assets, at September 30, 2013. Other real estate owned increased $430,000, or 10.4%, to $4.6 million at December 31, 2013 ($182,000 covered by FDIC loss sharing agreements) from $4.1 million at September 30, 2013 ($317,000 covered by FDIC loss sharing agreements). The increase was due primarily to the addition of five properties totaling $1.2 million partially offset by the disposition of five properties totaling $456,000 and valuation adjustments of $348,000.

Mr. Vance added, “We continue to see improvement in our overall credit metrics. Our non-performing originated assets have declined to just 0.68% of total originated assets and our allowance for loan losses remains at a healthy 1.76% of total loans or 329.4% of non-performing originated loans.”

Operating Results

Net interest income increased $1.9 million, or 12.3%, to $17.6 million for the quarter ended December 31, 2013 compared to $15.7 million for the same period in 2012. Net interest income increased $3.1 million, or 4.8%, to $67.7 million for the year ended December 31, 2013 compared to $64.6 million for the same period in 2012. The increases in net interest income are due to increases in average interest earning assets (substantially attributable to the NCB Acquisition and the Valley Acquisition) partially offset by declines in the net interest margin (substantially due to lower contractual loan note rates).

Heritage’s net interest margin for the quarter ended December 31, 2013 decreased 40 basis points to 4.58% from 4.98% for the same period in 2012 and decreased nine basis points from 4.67% in the linked-quarter ended September 30, 2013. The declines in net interest margin are due primarily to lower contractual loan note rates. Heritage’s net interest margin for the year ended December 31, 2013 decreased 37 basis points to 4.80% from 5.17% for the same period in 2012.

The positive effect on the net interest margin of discount accretion on the acquired loan portfolios for the quarter ended December 31, 2013 was approximately 38 basis points compared to 48 basis points in the same quarter of the prior year and 38 basis points for the linked-quarter ended September 30, 2013. Interest reversals on nonaccrual originated loans reduced the net interest margin for the quarter ended December 31, 2013 by approximately four basis points compared to six basis points for the same quarter in the prior year and four basis points for the linked-quarter ended September 30, 2013.

The positive effect on the net interest margin of discount accretion on the acquired loan portfolios was 48 basis points for the year ended December 31, 2013 compared to 50 basis points for the year ended December 31, 2012. Interest reversals on nonaccrual originated loans reduced the net interest margin for the year ended December 31, 2013 by five basis points compared to seven basis points for the prior year.

The provision for loan losses on originated loans was $(100,000) for the quarter ended December 31, 2013 compared to $280,000 for the quarter ended December 31, 2012 and $150,000 for the linked-quarter ended September 30, 2013. For the year ended December 31, 2013, the provision for loan losses on originated loans was $890,000 compared to $695,000 for the same period in the prior year.

The Company had net charge-offs on originated loans of $104,000 for the quarter ended December 31, 2013 compared to $1.7 million for the quarter ended December 31, 2012 and $615,000 for the linked-quarter ended September 30, 2013. For the year ended December 31, 2013, the Company had net charge-offs on originated loans of $2.9 million compared to $3.9 million for the prior year.

The provision for loan losses on purchased loans was $528,000 for the quarter ended December 31, 2013 compared to $419,000 for the same period in the prior year and $928,000 for the linked-quarter ended September 30, 2013. For the year ended December 31, 2013, the provision for loan losses on purchased loans was $2.8 million compared to $1.3 million for the prior year.

As of the acquisition dates, purchased loans were recorded at their estimated fair values, incorporating our estimate of future expected cash flows until the ultimate resolution of these credits. To the extent actual or projected cash flows are less than previously estimated, additional provisions for loan losses on the purchased loan portfolios are recognized immediately into earnings. To the extent actual or projected cash flows are more than previously estimated, the increase in cash flows is recognized immediately as a recapture of provision for loan losses up to the amount of any provision previously recognized for that pool of loans, if any, then prospectively recognized in interest income as a yield adjustment.

Cash flows on pools of acquired loans are re-estimated on a quarterly basis. As reflected in the table below, incremental accretion income was $1.46 million for the quarter ended December 31, 2013 compared to $1.45 million for the linked-quarter ended September 30, 2013. For the year ended December 31, 2013, incremental accretion income was $6.7 million compared to $6.3 million for the same period in the prior year.

For the quarter ended December 31, 2013, the Company recognized $155,000 of change in the FDIC indemnification asset compared to $(350,000) and $(346,000) for the quarters ended September 30, 2013 and December 31, 2012, respectively. The increase for the quarter ended December 31, 2013 as compared to the quarter ended September 30, 2013 was primarily due to a collateral valuation adjustment of a large purchased covered loan during the quarter ended December 31, 2013 which resulted in an addition to the FDIC indemnification asset.

The following table illustrates the significant accounting entries associated with the Company’s acquired loan portfolios:

Donald J. Hinson, Executive Vice President and Chief Financial Officer, commented, “Our net interest margin was a very respectable 4.58% for the fourth quarter of 2013. However, the net interest margin continues to experience compression due to the current low rate environment. The net interest margin before incremental accretion income decreased nine basis points to 4.20% for the quarter ended December 31, 2013 compared to 4.29% for the linked-quarter ended September 30, 2013. This decrease was driven primarily by lower contractual yields on the loan portfolio. Loan yields before incremental accretion income decreased eight basis points to 5.27% for the quarter ended December 31, 2013 compared to 5.35% for the linked-quarter ended September 30, 2013. This compression is expected to continue in the short-term as the average rates on new loans are lower than the current average yield of the loan portfolio.”

Noninterest income was $2.4 million for the quarter ended December 31, 2013 compared to $1.8 million for the same period in 2012 and $2.6 million for the linked-quarter ended September 30, 2013. The $656,000, or 37.0%, increase in the quarter ended December 31, 2013 from the same period in the prior year was primarily due to an increase of $501,000 in the change in FDIC indemnification asset and an increase of $143,000 in service charges and other fees.

For the year ended December 31, 2013, noninterest income was $9.7 million compared to $7.3 million for the year ended December 31, 2012. The $2.4 million, or 32.7%, increase was primarily due to a $596,000 gain on the sale of a branch building (included in “other income”), a $399,000 pre-tax bargain purchase gain on bank acquisition recognized during the first quarter of 2013 on the NCB Acquisition, an increase of $420,000 in service charges and other fees and an $852,000 improvement to income from the change in FDIC indemnification asset.

Noninterest expense was $18.5 million for the quarter ended December 31, 2013 compared to $12.4 million for the quarter ended December 31, 2012 and $14.3 million for the linked-quarter ended September 30, 2013. Noninterest expense increased $9.1 million, or 18.1%, to $59.5 million for the year ended December 31, 2013 from $50.4 million for the year ended December 31, 2012.

Current year initiatives had a significant impact on noninterest expense during 2013. In addition to the ongoing expenses associated with the addition of branches and personnel from the NCB Acquisition and the Valley Acquisition, there were expenses associated with implementation of these and other initiatives embarked upon during 2013. The following tables illustrate the expenses related to implementing these initiatives. The amounts reported represent identifiable costs paid to third party providers as well as any retention bonuses or severance payments made in conjunction with these initiatives. The amounts do not include costs of additional staffing required to be maintained in order to complete the initiatives. The first table reports these expenses by initiative and the second table reports these expenses by expense category.

The types of expenses associated with the significant expense categories in the table above are summarized as follows:

Jeffrey J. Deuel, President & Chief Operating Officer of Heritage Bank, commented “We are very proud of our team and their ability to successfully complete a core system conversion of Heritage Bank as well as the conversions of CVB and Valley in addition to effectively managing the balance of our 2013 efficiency initiatives.”

Income tax expense was $432,000 for the quarter ended December 31, 2013 compared to $1.3 million for the comparable quarter in 2012 and $1.5 million for the linked-quarter ended September 30, 2013. The decrease in income tax expense for the quarter ended December 31, 2013 from the prior periods was primarily due to the decrease in pre-tax income. The effective tax rate was 37.8% for quarter ended December 31, 2013 compared to 30.6% for the comparable quarter in 2012 and 31.5% for the linked-quarter ended September 30, 2013. The increase in the effective tax rate was due primarily to non-deductible expenses relating to the proposed Washington Banking merger.

Dividend

On January 29, 2014, the Company’s Board of Directors declared a quarterly cash dividend of $0.08 per common share payable on February 24, 2014 to shareholders of record on February 10, 2014.

Earnings Conference Call

The Company will hold a telephone conference call to discuss this earnings release on January 30, 2014 at 11:00 a.m. Pacific time. To access the call, please dial (800) 230-1093 a few minutes prior to 11:00 a.m., Pacific time. The call will be available for replay through February 13, 2014, by dialing (800) 475-6701 — access code 315328.

About Heritage Financial

Heritage Financial Corporation is an Olympia-based bank holding company with Heritage Bank, a full-service commercial bank, as its wholly-owned banking subsidiary. Following the opening of a new branch in Vancouver, Washington, on January 13, 2014, Heritage Bank now has thirty-six banking offices in Washington and Oregon. Heritage Bank does business under the Central Valley Bank name in the Yakima and Kittitas counties of Washington. The Company’s stock is traded on the NASDAQ Global Select Market under the symbol “HFWA”. More information about Heritage Financial Corporation can be found on its website at
www.hf-wa.com and more information about Heritage Bank can be found on its website at www.heritagebanknw.com.

Contact:

Brian L. Vance, President & Chief Executive Officer, (360) 943-1500

Donald J. Hinson, Executive Vice President & Chief Financial Officer, (360) 943-1500

Non-GAAP Financial Measures

This news release contains certain non-GAAP financial measures in addition to results presented in accordance with Generally Accepted Accounting Principles (GAAP). These measures include tangible common equity, tangible book value per share and tangible common equity to tangible assets. Tangible common equity (tangible book value) excludes goodwill and other intangible assets. Tangible assets exclude goodwill and other intangible assets. Management has presented these non-GAAP financial measures in this earnings release because it believes that they provide useful and comparative information to assess trends in the Company’s capital reflected in the current quarter and year-to-date results. Where applicable, the Company has also presented comparable capital information using GAAP financial measures. Reconciliations of the GAAP and non-GAAP financial measures are presented below.

Forward-Looking Statements

“Safe Harbor” statement under the Private Securities Litigation Reform Act of 1995: This release contains forward-looking statements that are subject to risks and uncertainties, including, but not limited to: the credit risks of lending activities, including changes in the level and trend of loan delinquencies and write-offs and changes in our allowance for loan losses and provision for loan losses that may be impacted by deterioration in the housing and commercial real estate markets; changes in general economic conditions, either nationally or in our market areas; changes in the levels of general interest rates, and the relative differences between short and long term interest rates, deposit interest rates, our net interest margin and funding sources; fluctuations in the demand for loans, the number of unsold homes and other properties and fluctuations in real estate values in our market areas; results of examinations of us by the Board of Governors of the Federal Reserve System and of our bank subsidiary by the Federal Deposit Insurance Corporation, the Washington State Department of Financial Institutions, Division of Banks or other regulatory authorities, including the possibility that any such regulatory authority may, among other things, require us to increase our allowance for loan losses, write-down assets, change our regulatory capital position or affect our ability to borrow funds or maintain or increase deposits, or impose additional requirements and restrictions on us, any of which could adversely affect our liquidity and earnings; legislative or regulatory changes that adversely affect our business including changes in regulatory policies and principles, including the interpretation of regulatory capital or other rules including changes related to Basel III; the impact of the Dodd-Frank Wall Street Reform and Consumer Protection Act and the implementing of regulations; our ability to control operating costs and expenses; the use of estimates in determining the fair value of certain of our assets, which estimates may prove to be incorrect and result in significant declines in valuation; difficulties in reducing risk associated with the loans on our balance sheet; staffing fluctuations in response to product demand or the implementation of corporate strategies that affect our workforce and potential associated charges; computer systems on which we depend could fail or experience a security breach; our ability to retain key members of our senior management team; costs and effects of litigation, including settlements and judgments; our ability to implement our expansion strategy; our ability to successfully integrate any assets, liabilities, customers, systems, and management personnel we have acquired including the Cowlitz Bank, Pierce Commercial Bank, Northwest Commercial Bank and Valley Community Bancshares transactions, or may in the future acquire into our operations, and our ability to realize related revenue synergies and cost savings within expected time frames and any goodwill charges related thereto; risks relating to acquiring assets or entering markets in which we have not previously

operated and may not be familiar; changes in consumer spending, borrowing and savings habits; the availability of resources to address changes in laws, rules, or regulations or to respond to regulatory actions; adverse changes in the securities markets; inability of key third-party providers to perform their obligations to us; changes in accounting policies and practices, as may be adopted by the financial institution regulatory agencies or the Financial Accounting Standards Board, including additional guidance and interpretation on accounting issues and details of the implementation of new accounting methods; other economic, competitive, governmental, regulatory, and technological factors affecting our operations, pricing, products and services; and other risks detailed from time to time in our filings with the Securities and Exchange Commission.

The Company cautions readers not to place undue reliance on any forward-looking statements. Moreover, you should treat these statements as speaking only as of the date they are made and based only on information then actually known to the Company. The Company does not undertake and specifically disclaims any obligation to revise any forward-looking statements to reflect the occurrence of anticipated or unanticipated events or circumstances after the date of such statements. These risks could cause our actual results for future periods to differ materially from those expressed in any forward-looking statements by, or on behalf of, us, and could negatively affect the Company’s operating and stock price performance.

Additional Information

Heritage has filed a registration statement on Form S-4 with the SEC in connection with the proposed transaction with Washington Banking. The registration statement includes a joint proxy statement of Heritage and Washington Banking that also constitutes a prospectus of Heritage, which will be sent to the shareholders of Heritage and Washington Banking. Shareholders are advised to read the joint proxy statement/prospectus because it contains important information about Heritage, Washington Banking and the proposed transaction. This document and other documents relating to the merger filed by Heritage and Washington Banking can be obtained free of charge from the SEC’s website at www.sec.gov. These documents also can be obtained free of charge by accessing Heritage’s website at http://www.hf-wa.com/docs.aspx?iid=1024198 or by accessing Washington Banking’s website at http://investor.washingtonbanking.info/docs.aspx?iid=1025104. Alternatively, these documents, can be obtained free of charge from Heritage upon written request to Heritage Financial Corporation, Secretary, 201 Fifth Avenue S.W., Olympia, WA 98501 or by calling (360) 943-1500, or from Washington Banking, upon written request to Washington Banking Company, Secretary, 450 SW Bayshore Drive, Oak Harbor, Washington 98277 or by calling (360) 240-6458.

Participants in this Transaction

Heritage, Washington Banking and certain of their respective directors and executive officers may be deemed to be participants in the solicitation of proxies from shareholders in connection with the proposed transaction under the rules of the SEC. Information about these participants may be found in the definitive proxy statement of Heritage relating to its 2013 Annual Meeting of Shareholders filed with the SEC by Heritage on March 19, 2013 and the definitive proxy statement of Washington Banking relating to its 2013 Annual Meeting of Shareholders filed with the SEC on March 26, 2013. These definitive proxy statements can be obtained free of charge from the sources indicated above. Additional information regarding the interests of these participants will also be included in the joint proxy statement/prospectus regarding the proposed transaction when it becomes available.

HERITAGE FINANCIAL CORPORATION

CONDENSED CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION

(Dollar amounts in thousands; unaudited)

HERITAGE FINANCIAL CORPORATION

CONDENSED CONSOLIDATED STATEMENTS OF INCOME

(Dollar amounts in thousands, except per share amounts; unaudited)

HERITAGE FINANCIAL CORPORATION

FINANCIAL STATISTICS

(Dollar amounts in thousands; unaudited)

HERITAGE FINANCIAL CORPORATION

FINANCIAL STATISTICS

(Dollar amounts in thousands; unaudited)