Exhibit 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We consent to the incorporation by reference in Registration Statement No. 333-107329 on Form S-8 of Westamerica Bancorporation of our report dated June 26, 2026 appearing in this Annual Report on Form 11-K of Westamerica Bancorporation Tax Deferred Savings/Retirement Plan (ESOP) for the year ended December 31, 2025.

/s/ Crowe LLP

South Bend, Indiana

June 26, 2026