Exhibit 99.13 Certification Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 with Respect to the FNB Bancorp Quarterly Report on Form 10-Q for the Quarter ended March 31, 2003 Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 (subsections (a) and (b) of section 1350, chapter 63 of title 18, United States Code), each of the undersigned officers of FNB Bancorp, a California corporation (the "Company"), does hereby certify that: 1. The Company's Quarterly Report on Form 10-Q for the quarter ended March 31, 2003 (the "Form 10-Q") fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended; and 2. Information contained in the Form 10-Q fairly presents, in all material respects, the financial condition and results of operations of the Company. Dated: May 13, 2003. /s/ Thomas C. McGraw -------------------------------- Thomas C. McGraw Chief Executive Officer Dated: May 13, 2003. /s/ James B. Ramsey --------------------------------- James B. Ramsey Senior Vice President and Chief Financial Officer