Westamerica Bancorporation Declares Quarterly Cash Dividend

SAN RAFAEL, Calif., Oct. 23, 2008 (GLOBE NEWSWIRE) -- The Board of Directors of
Westamerica Bancorporation (Nasdaq:WABC) today declared a quarterly cash
dividend of $0.35 per share on common stock outstanding to shareholders of
record at the close of business on November 3, 2008. The dividend is payable
November 14, 2008.

Chairman, President and CEO David Payne stated, "This dividend recognizes
Westamerica's healthy level of operating earnings, asset quality, and capital."

On October 15, 2008, Westamerica reported $39 million in net income for the nine
months ended September 30, 2008, generating 13 percent return on shareholders'
equity.

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

Westamerica Bancorporation Web Address: www.westamerica.com

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
September 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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CONTACT: Westamerica Bancorporation
Robert A. Thorson - SVP & Chief Financial Officer
707-863-6840