Westamerica Bank

September 11, 2008

FOR IMMEDIATE RELEASE
                                                                                   
 
San Rafael, CA:  Westamerica Bancorporation (NASDAQ:  WABC) is scheduled to participate in the RBC Capital Markets 2008 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 16, 2008.  Investors and the public can access the audio-only webcast at http://www.wsw.com/webcast/rbc92/register.aspx?conf=rbc92&page=panel1&url=http%3A//www.wsw.com/webcast/rbc92/panel1/ or go to https://www.westamerica.com/index.php?option=com_content&view=article&id=358&catid=56&Itemid=192 and follow the links to the webcast.

Westamerica Bancorporation through its wholly owned subsidiary, Westamerica Bank, operates 86 branches and two trust offices throughout 21 Northern and Central California counties.

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 annual and quarterly reports filed with the Securities and Exchange Commission, including the Company's Form 10-Q for the quarter ended June 30, 2008 and Form 10-K for the year ended December 31, 2007, 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 Sarbanes-Oxley Act of 2002 and the Gramm-Leach-Bliley Act of 1999, 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.

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For additional information contact:

Westamerica Bancorporation
Robert A. Thorson, Senior Vice President and Chief Financial Officer, (707) 863-6840
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