Exhibit 99.1

UNAUDITED PRO FORMA

COMBINED CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

The following unaudited pro forma combined condensed consolidated financial statements are based on the separate historical financial statements of TriCo Bancshares (“TriCo”) and FNB Bancorp (“FNB”) after giving effect to the merger of FNB into TriCo (the “Merger”) and the issuance of TriCo common stock in connection therewith, and the assumptions and adjustments described in the accompanying notes to the unaudited pro forma combined condensed consolidated financial statements. The unaudited pro forma condensed consolidated balance sheet as of March 31, 2018 is presented as if the Merger had occurred on March 31, 2018. The unaudited pro forma condensed consolidated income statements for the year ended December 31, 2017 and the three months ended March 31, 2018 are presented as if the Merger had occurred on January 1, 2017. The historical consolidated financial information has been adjusted to reflect factually supportable items that are directly attributable to the Merger and, with respect to the income statements only, expected to have a continuing impact on consolidated results of operations.

In connection with the integration of the operations of TriCo and FNB following the completion of the Merger, TriCo has incurred nonrecurring charges, such as costs associated with systems implementation, data conversion, severance, professional fees, and other costs related to exit or disposal activities. These charges will affect the results of operations of TriCo in the periods in which they are incurred. The unaudited pro forma combined condensed consolidated statements of earnings do not include the effects of the costs associated with any restructuring or integration activities resulting from the transaction, as they are nonrecurring in nature. Additionally, the unaudited pro forma adjustments do not give effect to any nonrecurring or unusual restructuring charges that may be incurred as a result of the integration of the two companies or any anticipated disposition of assets that may result from such integration. However, the unaudited pro forma combined condensed consolidated balance sheets reflect the payment of merger costs specified therein as a reduction in cash and pro forma shareholders’ equity.

The unaudited pro forma combined condensed consolidated financial statements are provided for informational purposes only. The unaudited pro forma combined condensed consolidated financial statements are not necessarily, and should not be assumed to be, an indication of the results that would have been achieved had the transaction been completed as of the dates indicated or that may be achieved in the future. The actual amounts recorded may differ materially from the information presented in these unaudited pro forma condensed consolidated financial statements as a result of material and significant information becoming known that was previously not expected or known; and changes in the financial results of the combined company, which could change the future discounted cash flow projections. The preparation of the unaudited pro forma combined condensed consolidated financial statements and related adjustments required management to make certain assumptions and estimates. The unaudited pro forma combined condensed consolidated financial statements should be read together with:

Unaudited Pro Forma Combined Condensed Consolidated Balance Sheet

as of March 31, 2018

(Dollars in Thousands)

Unaudited Pro Forma Combined Condensed Consolidated Statement of Earnings

Three Months Ended March 31, 2018

(In thousands, except per share amounts)

The unaudited pro forma condensed combined statement of income for the three months ended March 31, 2018 presents the consolidated financial results as if the merger had occurred on January 1, 2017.

Unaudited Pro Forma Combined Condensed Consolidated Statement of Earnings

Year Ended December 31, 2017

(In thousands, except per share amounts)

The unaudited pro forma condensed combined statement of income for the year ended December 31, 2017 presents the consolidated financial results as if the merger had occurred on January 1, 2017.

Note 1—Basis of Presentation

The unaudited pro forma condensed combined financial information has been prepared using the acquisition method of accounting giving effect to the merger involving TriCo and FNB. The unaudited pro forma condensed combined financial information is presented for illustrative purposes only and is not necessarily indicative of the financial position had the merger been consummated at March 31, 2018 or the results of operations had the merger been consummated at January 1, 2017, nor is it necessarily indicative of the results of operation in future periods or the future financial position of the combined entities. The merger was completed on July 6, 2018. The merger consideration included the issuance of approximately $284.4 million in equity consideration as well as cash consideration of approximately $6.7 million.

Under the acquisition method of accounting, the assets and liabilities of FNB will be recorded at their respective fair values on the merger date. The fair value on the merger date represents management’s best estimates based on available information and facts and circumstances in existence on the merger date. Although the purchase price is indicative of the actual purchase price, the pro forma adjustments reflected in the unaudited pro forma condensed combined financial information is subject to change and may vary from the actual purchase price allocation that will be recorded when the accounting for the merger is completed. Adjustments may include, but not be limited to, changes in (i) FNB’s balance sheet through the effective time of the merger; (ii) total merger related expenses if consummation and/or implementation costs vary from currently estimated amounts; and (iii) the underlying values of assets and liabilities if market conditions differ from current assumptions.

The accounting policies of both TriCo and FNB are in the process of being reviewed in detail. Upon completion of such review, conforming adjustments or financial statement reclassification may be determined necessary.

Note 2—Estimated Merger and Integration Costs

In connection with the merger, the integration of TriCo’s and FNB’s operations is underway, with the system conversion occurring during the month of acquisition. Trico expects to incur merger-related expenses and other expenditures including system implementation, data conversion, employee retention and severance, communications with customers and vendors, facility upgrades, and other potentially significant costs. To the extent there are costs associated with these actions, the costs will be recorded based on the nature and timing of these integration actions. Most acquisition costs are recognized separately from a business combination and generally will be expensed as incurred. We expect that the majority of merger related costs will be incurred during 2018.

Note 3—Pro Forma Adjustments

The following pro forma adjustments have been reflected in the unaudited pro forma condensed combined financial information. All taxable adjustments to deferred tax assets and liabilities were calculated using a 29.56% effective tax rate. Adjustments to the income tax provision were calculated using a 29.56% effective tax rate for the period ending March 31, 2018, and a 42.05% effective tax rate for the period ending December 31, 2017. All adjustments are based on current assumptions and valuations, which are subject to change.

Notes to Pro Forma Balance Sheet Adjustments (dollars in thousands)