Westamerica Bank

September 11, 2009

FOR IMMEDIATE RELEASE

San Rafael, CA:  Westamerica Bancorporation (NASDAQ:  WABC) is scheduled to participate in the RBC Capital Markets 2009 Financial Institutions Conference.

David Payne, Chairman, President and CEO, will participate in the "Bank Credit: When Will Nonperforming Assets Peak? " panel discussion beginning at 8:30 a.m. ET on Tuesday, September 22, 2009. Investors and the public can access the audio-only webcast at:  http://wsw.com/webcast/rbc105/panel1 .

Mr. Payne will also participate in the "M&A: Distressed Acquisition Opportunities" panel discussion beginning at 3:15 p.m. ET on Wednesday, September 23, 2009.  Investors and the public can access the audio-only webcast at:  http://wsw.com/webcast/rbc105/panel14/ .

Westamerica Bancorporation, through its wholly owned subsidiary, Westamerica Bank, operates 99 branches and two trust offices throughout Northern and Central California counties.

FORWARD-LOOKING INFORMATION:

This press release contains forward-looking statements about Westamerica Bancorporation for which it claims the protection of the safe harbor provisions contained in the Private Securities Litigation Reform Act of 1995. Examples of forward-looking statements include, but are not limited to: (i) projections of revenues, expenses, income or loss, earnings or loss per share, the payment or nonpayment of dividends, capital structure and other financial items; (ii) statements of plans, objectives and expectations of the Company or its management or board of directors, including those relating to products or services; (iii) statements of future economic performance; and (iv) statements of assumptions underlying such statements. Words such as "believes", "anticipates", "expects", "intends", "targeted", "projected", "continue", "remain", "will", "should", "may" and other similar expressions are intended to identify forward-looking statements but are not the exclusive means of identifying such statements.

These forward-looking statements are based on Management’s current knowledge and belief and include information concerning the Company’s possible or assumed future financial condition and results of operations. A number of factors, some of which are beyond the Company’s ability to predict or control, could cause future results to differ materially from those contemplated. The Company’s most recent quarterly report on Form 10-Q for the quarter ended June 30, 2009 and annual report on Form 10-K for the year ended December 31, 2008 filed with the Securities and Exchange Commission describe some of these factors. These factors include but are not limited to (1) the length and severity of current difficulties in the national and California economies and the effects of federal and state government efforts to address those difficulties; (2) continued low liquidity levels in capital markets; (3) fluctuations in asset prices including, but not limited to, stocks, bonds, real estate, and commodities; (4) the effect of acquisitions and integration of acquired businesses including the recently acquired County Bank; (5) economic uncertainty created by terrorist threats and attacks on the United States, the actions taken in response, and the uncertain effect of these events on the national and regional economies; (6) changes in the interest rate environment; (7) changes in the regulatory environment; (8) significantly increasing competitive pressure in the banking industry; (9) operational risks including data processing system failures or fraud; (10) volatility of rate sensitive loans, deposits and investments; (11) asset/liability management risks and liquidity risks; and (12) changes in the securities markets. The Company undertakes no obligation to update any forward-looking statements to reflect circumstances or events that occur after the date forward-looking statements are made.

Forward-looking statements speak only as of the date they are made.

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