Exhibit 99.1

FOR IMMEDIATE RELEASE
January 20, 2011

WESTAMERICA BANCORPORATION REPORTS
FOURTH QUARTER 2010 RESULTS

San Rafael, CA: Westamerica Bancorporation (NASDAQ: WABC), parent company of Westamerica Bank, today reported fourth quarter 2010 net income applicable to common equity of $23.7 million, or $0.81 diluted earnings per share (“EPS”), compared to $23.7 million, or $0.81 EPS in the prior quarter, and $23.3 million, or $0.79 EPS in the fourth quarter 2009. Fourth quarter 2010 net income applicable to common equity represents an 18 percent annualized return on average common equity.

“Westamerica’s net interest margin was 5.39 percent in the fourth quarter 2010. Yields on loans and investment securities are relatively low in the current interest rate environment, which has caused a reduction in asset yields. Our focus on checking and savings deposits delivered a 0.29 percent cost of funding our loans and securities, a much lower funding cost than our peers. We have worked diligently to operate efficiently in spite of cyclically higher problem loan workout costs and FDIC insurance assessments. From our total revenues of $72 million in the fourth quarter 2010, only $32 million was spent on operating expenses, delivering well over one-half of our revenue as pre-tax income for our shareholders,” said Chairman, President and CEO David Payne. “The credit quality of legacy Westamerica assets improved during the quarter as nonperforming assets declined $6 million to $33 million at December 31, 2010. Purchased nonperforming assets declined $12 million to $111 million at December 31, 2010, of which $69 million are indemnified by the FDIC under loss-sharing agreements. Common shareholders’ equity increased to $545 million at December 31, 2010 resulting in a total regulatory capital ratio of 15.5 percent,” Payne added.

Net interest income on a fully taxable equivalent basis (FTE) was $56.4 million for the fourth quarter 2010, compared to $56.7 million (FTE) for the prior quarter and $58.9 million (FTE) for the fourth quarter 2009. The fourth quarter 2010 annualized net interest margin was 5.39 percent (FTE), compared to 5.54 percent (FTE) for the prior quarter and 5.50 percent (FTE) for the fourth quarter 2009. The decline in net interest margin from the prior quarter is due to a decline in yields on loans and investment securities; current market yields are generally lower than yields on existing portfolios. The decline in net interest income in the fourth quarter 2010 compared to the fourth quarter 2009 is attributable to a lower net interest margin and lower levels of loans; loans have declined due to weak economic conditions and weak loan demand.

The provision for loan losses was $2.8 million for the fourth quarter 2010, unchanged from the prior quarter and down from $3.3 million for the fourth quarter 2009.

Noninterest income for the fourth quarter 2010 was $15.1 million, compared to $15.1 million in the prior quarter and $15.7 million the fourth quarter 2009. Service charges on deposit accounts were lower in both the fourth quarter 2010 and third quarter 2010 compared to the fourth quarter 2009 due to new overdraft regulations which were effective July 1, 2010.

Noninterest expense for the fourth quarter of 2010 totaled $31.5 million, unchanged from the prior quarter, and reduced from $32.8 million for the fourth quarter 2009. Westamerica continually manages its expense base as a general business practice in light of industry developments and economic conditions.

Non-performing originated assets totaled $33 million at December 31, 2010, reduced $6 million from September 30, 2010. Excluding repossessed loan collateral, nonperforming originated loans were $21.6 million compared to the allowance for loan losses of $35.6 million at December 31, 2010. Non-performing purchased loans indemnified by the Federal Deposit Insurance Corporation totaled $48 million at December 31, 2010 reduced from $56 million at September 30, 2010; such loans were measured at estimated fair value on the February 6, 2009 acquisition date. Nonperforming non-indemnified purchased loans totaled $39 million at December 31, 2010 compared to $38 million at September 30, 2010; such loans were measured at estimated fair value on the August 20, 2010 acquisition date.

Shareholders’ equity at December 31, 2010 was $545 million, increased from $541 million at September 30, 2010. Westamerica paid a regular quarterly dividend of $0.36 per common share in November 2010, totaling $10.5 million. At December 31, 2010, Westamerica Bancorporation’s total regulatory capital ratio was 15.5 percent and Westamerica Bank’s total regulatory capital ratio was 15.3 percent; both measurements exceed the “well-capitalized” level of ten percent under regulatory requirements.

Westamerica operates commercial banking offices throughout Northern and Central California. At December 31, 2010, Westamerica’s total assets and total loans outstanding were $4.9 billion and $2.9 billion, respectively.

Westamerica Bancorporation Web Address: www.westamerica.com

For additional information contact:

Westamerica Bancorporation
Robert A. Thorson — SVP & Chief Financial Officer
707-863-6840

FORWARD-LOOKING INFORMATION:

The following appears in accordance with the Private Securities Litigation Reform Act of 1995:

This press release may contain forward-looking statements about the Company, including descriptions of plans or objectives of its management for future operations, products, or services, and forecasts of its revenues, earnings or other measures of economic performance. Forward-looking statements can be identified by the fact that they do not relate strictly to historical or current facts. They often include the words “believe,” “expect,” “anticipate,” “intend,” “plan,” “estimate,” or words of similar meaning, or future or conditional verbs such as “will,” “would,” “should,” “could,” or “may.”

Forward-looking statements, by their nature, are subject to risks and uncertainties. A number of factors — many of which are beyond the Company’s control — could cause actual conditions, events or results to differ significantly from those described in the forward-looking statements. The Company’s most recent reports filed with the Securities and Exchange Commission, including the annual report for the year ended December 31, 2009 filed on Form 10-K and quarterly report for the quarter ended September 30, 2010 filed on Form 10-Q, describe some of these factors, including certain credit, market, operational, liquidity and interest rate risks associated with the Company’s business and operations. Other factors described in these reports include changes in business and economic conditions, competition, fiscal and monetary policies, disintermediation, legislation including the Dodd Frank Wall Street Reform and Consumer Protection Act of 2010, and the Sarbanes-Oxley Act of 2002, and mergers and acquisitions.

Forward-looking statements speak only as of the date they are made. The Company does not undertake to update forward-looking statements to reflect circumstances or events that occur after the date forward looking statements are made.

#####

Public Information January 20, 2011

WESTAMERICA BANCORPORATION
FINANCIAL HIGHLIGHTS
December 31, 2010

1. Net Income Summary.

						(dollars in thousands except per-share amounts)
														Q4’10 /								Q4’10 /												12/31’10YTD /
						Q4’10				Q4’09				Q4’09				Q3’10				Q3’10				12/31’10YTD				12/31’09YTD				12/31’09YTD
	1			Net Interest Income (Fully Taxable Equivalent)		$	56,413			$	58,949				-4.3	%		$	56,669				-0.5	%		$	226,683			$	242,218				-6.4	%
	2			Provision for Loan Losses			2,800				3,300				-15.2	%			2,800				0.0	%			11,200				10,500				6.7	%
	3			Noninterest Income:
	4			Gain on Acquisition			0				0				n/m				178				n/m				178				48,844				n/m
	5			Other			15,142				15,696				-3.5	%			14,893				1.7	%			61,276				63,167				-3.0	%
	6			Total Noninterest Income			15,142				15,696				-3.5	%			15,071				0.5	%			61,454				112,011				n/m
	7			Noninterest Expense			31,512				32,836				-4.0	%			31,508				0.0	%			127,147				140,776				-9.7	%
	8			Income Before Taxes (FTE)			37,243				38,509				-3.3	%			37,432				-0.5	%			149,790				202,953				n/m
	9			Income Tax Provision (FTE)			13,512				14,348				-5.8	%			13,723				-1.5	%			55,213				77,527				n/m
	10			Net Income			23,731				24,161				-1.8	%			23,709				0.1	%			94,577				125,426				n/m
	11			Preferred Stock Dividends and Discount Accretion			0				812				n/m				0				n/m				0				3,963				n/m
	12			Net Income Applicable to Common Equity		$	23,731			$	23,349				1.6	%		$	23,709				0.1	%		$	94,577			$	121,463				n/m
	13			Average Common Shares Outstanding			29,103				29,205				-0.3	%			29,127				-0.1	%			29,166				29,105				0.2	%
	14			Diluted Average Common Shares Outstanding			29,341				29,471				-0.4	%			29,385				-0.1	%			29,471				29,353				0.4	%
	15			Operating Ratios:
	16			Basic Earnings Per Common Share		$	0.82			$	0.80				2.5	%		$	0.81				0.3	%		$	3.24			$	4.17				n/m
	17			Diluted Earnings Per Common Share			0.81				0.79				2.5	%			0.81				0.0	%			3.21				4.14				n/m
	18			Return On Assets (annualized)			1.87	%			1.85	%							1.95	%							1.95	%			2.39	%
	19			Return On Common Equity (annualized)			17.5	%			18.8	%							17.9	%							18.1	%			25.8	%
	20			Net Interest Margin (FTE) (annualized)			5.39	%			5.50	%							5.54	%							5.54	%			5.42	%
	21			Efficiency Ratio (FTE)			44.0	%			44.0	%							43.9	%							44.1	%			39.7	%
	22			Dividends Paid Per Common Share		$	0.36			$	0.35				2.9	%		$	0.36				0.0	%		$	1.44			$	1.41				2.1	%
	23			Common Dividend Payout Ratio			44	%			44	%							44	%							45	%			34	%

2. Net Interest Income.

						(dollars in thousands)
														Q4’10 /								Q4’10 /												12/31’10YTD /
						Q4’10				Q4’09				Q4’09				Q3’10				Q3’10				12/31’10YTD				12/31’09YTD				12/31’09YTD
	1			Interest and Fee Income (FTE)		$	59,477			$	63,250				-6.0	%		$	59,765				-0.5	%		$	239,523			$	261,598				-8.4	%
	2			Interest Expense			3,064				4,301				-28.8	%			3,096				-1.0	%			12,840				19,380				-33.7	%
	3			Net Interest Income (FTE)		$	56,413			$	58,949				-4.3	%		$	56,669				-0.5	%		$	226,683			$	242,218				-6.4	%
	4			Average Earning Assets		$	4,164,013			$	4,268,101				-2.4	%		$	4,068,561				2.3	%		$	4,094,511			$	4,472,660				-8.5	%
	5			Average Interest-Bearing Liabilities			2,964,999				2,985,494				-0.7	%			2,830,355				4.8	%			2,849,262				3,136,144				-9.1	%
	6			Yield on Earning Assets (FTE) (annualized)			5.68	%			5.90	%							5.84	%							5.85	%			5.85	%
	7			Cost of Funds (annualized)			0.29	%			0.40	%							0.30	%							0.31	%			0.43	%
	8			Net Interest Margin (FTE) (annualized)			5.39	%			5.50	%							5.54	%							5.54	%			5.42	%
	9			Interest Expense/Interest-Bearing Liabilities (annualized)			0.41	%			0.57	%							0.43	%							0.45	%			0.62	%
	10			Net Interest Spread (FTE) (annualized)			5.27	%			5.33	%							5.41	%							5.40	%			5.23	%

3. Loans & Other Earning Assets.

						(average volume, dollars in thousands)
														Q4’10 /								Q4’10 /												12/31’10YTD /
						Q4’10				Q4’09				Q4’09				Q3’10				Q3’10				12/31’10YTD				12/31’09YTD				12/31’09YTD
	1			Total Assets		$	5,032,157			$	5,007,341				0.5	%		$	4,835,357				4.1	%		$	4,853,480			$	5,086,637				-4.6	%
	2			Total Earning Assets			4,164,013				4,268,101				-2.4	%			4,068,561				2.3	%			4,094,511				4,472,660				-8.5	%
	3			Total Loans			2,958,095				3,124,583				-5.3	%			2,937,501				0.7	%			2,954,033				3,226,961				-8.5	%
	4			Commercial Loans			744,830				848,704				-12.2	%			772,997				-3.6	%			771,834				894,747				-13.7	%
	5			Commercial Real Estate Loans			1,283,836				1,265,086				1.5	%			1,234,475				4.0	%			1,245,369				1,283,114				-2.9	%
	6			Consumer Loans			929,429				1,010,793				-8.0	%			930,029				-0.1	%			936,830				1,049,100				-10.7	%
	7			Total Investment Securities			1,205,918				1,143,518				5.5	%			1,131,060				6.6	%			1,140,478				1,245,699				-8.4	%
	8			Available For Sale (Market Value)			601,764				392,229				53.4	%			489,581				22.9	%			483,214				407,498				18.6	%
	9			Held To Maturity			604,154				751,289				-19.6	%			641,479				-5.8	%			657,264				838,201				-21.6	%
	10			HTM Unrealized Gain at Period-End			13,983				9,335				n/m				24,044				n/m				13,983				9,335				n/m
	11			Loans / Deposits			71.1	%			76.7	%							73.8	%							73.9	%			79.3	%

Public Information January 20, 2011

WESTAMERICA BANCORPORATION
FINANCIAL HIGHLIGHTS
December 31, 2010

4. Deposits & Other Interest-Bearing Liabilities.

						(average volume, dollars in thousands)
														Q4’10 /								Q4’10 /												12/31’10YTD /
						Q4’10				Q4’09				Q4’09				Q3’10				Q3’10				12/31’10YTD				12/31’09YTD				12/31’09YTD
	1			Total Deposits		$	4,159,497			$	4,074,105				2.1	%		$	3,981,437				4.5	%		$	3,998,490			$	4,068,388				-1.7	%
	2			Noninterest Demand			1,468,098				1,425,867				3.0	%			1,417,638				3.6	%			1,412,702				1,354,534				4.3	%
	3			Interest-Bearing Transaction			721,521				669,519				7.8	%			678,524				6.3	%			682,278				696,638				-2.1	%
	4			Savings			1,063,554				979,973				8.5	%			993,934				7.0	%			994,604				951,457				4.5	%
	5			Time greater than $100K			556,635				564,539				-1.4	%			549,459				1.3	%			550,810				607,642				-9.4	%
	6			Time less than $100K			349,689				434,207				-19.5	%			341,882				2.3	%			358,096				458,117				-21.8	%
	7			Total Short-Term Borrowings			181,349				225,011				-19.4	%			203,841				-11.0	%			202,663				316,306				-35.9	%
	8			Fed Funds Purchased			0				0				n/m				0				n/m				0				107,732				n/m
	9			Other Short-Term Funds			181,349				225,011				-19.4	%			203,841				-11.0	%			202,663				208,574				-2.8	%
	10			Federal Home Loan Bank Advances			65,868				85,728				n/m				36,298				n/m				34,378				79,417				n/m
	11			Long-Term Debt			26,383				26,517				-0.5	%			26,417				-0.1	%			26,433				26,567				-0.5	%
	12			Shareholders’ Equity			537,204				514,497				4.4	%			525,630				2.2	%			522,183				524,324				-0.4	%
	13			Demand Deposits / Total Deposits			35.3	%			35.0	%							35.6	%							35.3	%			33.3	%
	14			Transaction & Savings Deposits / Total Deposits			78.2	%			75.5	%							77.6	%							77.3	%			73.8	%

5. Interest Yields Earned & Rates Paid.

						(dollars in thousands)
						Q4’10												Q3’10				Q4’09
						Average				Income/				Yield */				Yield*/				Average				Income/				Yield*/
						Volume				Expense				Rate				Rate				Volume				Expense				Rate
	1			Interest & Fees Income Earned
	2			Total Earning Assets (FTE)		$	4,164,013			$	59,477				5.68	%			5.84	%		$	4,268,101			$	63,250				5.90	%
	3			Total Loans (FTE)			2,958,095				44,929				6.03	%			6.13	%			3,124,583				47,694				6.06	%
	4			Commercial Loans (FTE)			744,830				12,021				6.40	%			6.29	%			848,704				12,498				5.84	%
	5			Commercial Real Estate Loans			1,283,836				20,526				6.34	%			6.65	%			1,265,086				21,119				6.62	%
	6			Consumer Loans			929,429				12,382				5.29	%			5.30	%			1,010,793				14,077				5.53	%
	7			Total Investment Securities (FTE)			1,205,918				14,548				4.83	%			5.09	%			1,143,518				15,556				5.44	%
	8			Interest Expense Paid
	9			Total Earning Assets			4,164,013				3,064				0.29	%			0.30	%			4,268,101				4,301				0.40	%
	10			Total Interest-Bearing Liabilities			2,964,999				3,064				0.41	%			0.43	%			2,985,494				4,301				0.57	%
	11			Total Interest-Bearing Deposits			2,691,399				2,002				0.30	%			0.32	%			2,648,238				3,024				0.45	%
	12			Interest-Bearing Transaction			721,521				233				0.13	%			0.13	%			669,519				238				0.14	%
	13			Savings			1,063,554				585				0.22	%			0.27	%			979,973				803				0.33	%
	14			Time less than $100K			349,689				345				0.39	%			0.41	%			434,207				845				0.77	%
	15			Time greater than $100K			556,635				839				0.60	%			0.58	%			564,539				1,138				0.80	%
	16			Total Short-Term Borrowings			181,349				453				0.98	%			0.98	%			225,011				560				0.98	%
	17			Fed Funds Purchased			0				0				0.00	%			0.00	%			0				0				0.00	%
	18			Other Short-Term Funds			181,349				453				0.98	%			0.98	%			225,011				560				0.98	%
	19			Federal Home Loan Bank Advances			65,868				187				1.11	%			1.22	%			85,728				295				1.35	%
	20			Long-Term Debt			26,383				422				6.40	%			6.43	%			26,517				422				6.36	%
	21			Net Interest Income and Margin (FTE)						$	56,413				5.39	%			5.54	%						$	58,949				5.50	%

6. Noninterest Income.

						(dollars in thousands except per share amounts)
														Q4’10 /								Q4’10 /												12/31’10YTD /
						Q4’10				Q4’09				Q4’09				Q3’10				Q3’10				12/31’10YTD				12/31’09YTD				12/31’09YTD
	1			Service Charges on Deposit Accounts		$	7,984			$	9,376				-14.8	%		$	8,162				-2.2	%		$	33,517			$	36,392				-7.9	%
	2			Merchant Credit Card Income			2,427				2,250				7.9	%			2,234				8.6	%			9,057				9,068				-0.1	%
	3			ATM Fees & Interchange			930				901				3.3	%			1,004				-7.4	%			3,848				3,693				4.2	%
	4			Debit Card Fees			1,210				1,219				-0.8	%			1,259				-3.9	%			4,888				4,875				0.3	%
	5			Financial Services Commissions			164				163				0.5	%			211				-22.5	%			747				583				28.2	%
	6			Mortgage Banking Income			30				14				n/m				23				32.4	%			112				82				36.2	%
	7			Trust Fees			447				373				19.9	%			429				4.4	%			1,705				1,429				19.3	%
	8			Other Income			1,950				1,400				39.2	%			1,571				24.1	%			7,402				7,045				5.1	%
	9			Sub-total			15,142				15,696				-3.5	%			14,893				1.7	%			61,276				63,167				-3.0	%
	10			Gain on Acquisition			0				0				n/m				178				n/m				178				48,844				n/m
	11			Total Noninterest Income		$	15,142			$	15,696				-3.5	%		$	15,071				0.5	%		$	61,454			$	112,011				n/m
	12			Operating Ratios:
	13			Total Revenue (FTE)		$	71,555			$	74,645				-4.1	%		$	71,740				-0.3	%		$	288,137			$	354,229				n/m
	14			Noninterest Income / Revenue (FTE)			21.2	%			21.0	%							21.0	%							21.3	%			31.6	%
	15			Service Charges / Avg. Deposits (annualized)			0.76	%			0.91	%							0.81	%							0.84	%			0.89	%
	16			Total Revenue Per Avg. Common Share (annualized)		$	9.75			$	10.14				-3.8	%		$	9.77				-0.2	%		$	9.88			$	12.17				n/m

Public Information January 20, 2011

WESTAMERICA BANCORPORATION
FINANCIAL HIGHLIGHTS
December 31, 2010

						(dollars in thousands)
														Q4’10 /								Q4’10 /												12/31’10YTD /
						Q4’10				Q4’09				Q4’09				Q3’10				Q3’10				12/31’10YTD				12/31’09YTD				12/31’09YTD
	1			Salaries & Benefits		$	14,899			$	15,170				-1.8	%		$	15,481				-3.8	%		$	61,748			$	65,391				-5.6	%
	2			Occupancy			4,073				3,917				4.0	%			3,962				2.8	%			15,633				18,748				-16.6	%
	3			Equipment			1,091				1,240				-12.0	%			1,067				2.3	%			4,325				5,859				-26.2	%
	4			Outsourced Data Processing			2,328				2,260				3.0	%			2,187				6.5	%			8,957				9,000				-0.5	%
	5			Courier			859				927				-7.4	%			826				3.9	%			3,495				3,808				-8.2	%
	6			Postage			289				540				-46.5	%			322				-10.3	%			1,540				2,110				-27.0	%
	7			Telephone			448				490				-8.4	%			346				29.6	%			1,590				1,977				-19.6	%
	8			Professional Fees			896				1,003				-10.7	%			950				-5.7	%			3,376				3,583				-5.8	%
	9			Stationery & Supplies			329				364				-9.7	%			276				19.5	%			1,285				1,555				-17.4	%
	10			Loan Expense			391				342				14.3	%			354				10.4	%			1,639				2,031				-19.3	%
	11			Operational Losses			213				295				-27.7	%			237				-10.2	%			828				953				-13.1	%
	12			Amortization of Identifiable Intangibles			1,622				1,646				-1.5	%			1,573				3.1	%			6,333				6,697				-5.4	%
	13			FDIC Insurance Assessment			1,320				1,440				-8.3	%			1,268				4.1	%			5,168				6,260				-17.4	%
	14			Other Operating			2,754				3,202				-14.0	%			2,659				3.6	%			11,230				12,804				-12.3	%
	15			Total Noninterest Expense		$	31,512			$	32,836				-4.0	%		$	31,508				0.0	%		$	127,147			$	140,776				-9.7	%
	16			Average (Avg.) Full Time Equivalent Staff			1,006				1,056				-4.7	%			1,004				0.2	%			1,015				1,115				-9.0	%
	17			Avg. Assets / Avg. Full Time Equivalent Staff		$	5,002			$	4,742				5.5	%		$	4,816				3.9	%		$	4,782			$	4,562				4.8	%
	18			Operating Ratios:
	19			FTE Revenue / Avg. Full Time Equiv. Staff (annualized)		$	282			$	280				0.7	%		$	283				-0.4	%		$	284			$	318				-10.7	%
	20			Noninterest Expense / Avg. Earning Assets (annualized)			3.00	%			3.05	%							3.07	%							3.11	%			3.15	%
	21			Noninterest Expense / FTE Revenues			44.0	%			44.0	%							43.9	%							44.1	%			39.7	%

8. Provision for Loan Losses.

						(dollars in thousands)
														Q4’10 /								Q4’10 /												12/31’10YTD /
						Q4’10				Q4’09				Q4’09				Q3’10				Q3’10				12/31’10YTD				12/31’09YTD				12/31’09YTD
	1			Average Total Loans		$	2,958,095			$	3,124,583				-5.3	%		$	2,937,501				0.7	%		$	2,954,033			$	3,226,961				-8.5	%
	2			Avg. Total Purchased Covered Loans (1)			704,728				889,101				-20.7	%			743,126				-5.2	%			766,369				897,942				-14.7	%
	3			Avg. Total Purchased Non-Covered Loans (2)			207,450				0				n/m				97,438				112.9	%			76,158				0				n/m
	4			Avg. Total Originated Loans			2,045,917				2,235,482				-8.5	%			2,096,937				-2.4	%			2,111,506				2,329,019				-9.3	%
	5			Provision for Loan Losses		$	2,800			$	3,300				-15.2	%		$	2,800				0.0	%		$	11,200			$	10,500				6.7	%
	6			Gross Loan Losses			6,342				6,533				-2.9	%			5,216				21.6	%			20,268				17,267				17.4	%
	7			Net Loan Losses			5,293				4,940				7.1	%			4,387				20.6	%			16,607				13,927				19.2	%
	8			Recoveries / Gross Loan Losses			17	%			24	%							16	%							18	%			19	%
	9			Net Loan Losses / Avg. Originated Loans (a)			1.03	%			0.88	%							0.83	%							0.79	%			0.60	%
	10			Provision for Loan Losses / Avg. Originated Loans (a)			0.54	%			0.59	%							0.53	%							0.53	%			0.45	%
	11			Provision for Loan Losses / Net Loan Losses			52.9	%			66.8	%							63.8	%							67.4	%			75.4	%