12 CFR § 7.3000 - National bank hours and closings.
(a) Bank hours. A national bank's board of directors should review its banking hours, and, independently of any other bank, take appropriate action to establish a schedule of banking hours.
(b) Emergency closings. Pursuant to 12 U.S.C. 95(b)(1), the Comptroller of the Currency (Comptroller), a state, or a legally authorized state official may declare a day a legal holiday if emergency conditions exist. That day is a legal holiday for national banks or their offices in the affected geographic area (i.e., throughout the country, in a state, or in part of a state). Emergency conditions include natural disasters and civil and municipal emergencies (e.g., severe flooding, or a power emergency declared by a local power company or government requesting that businesses in the affected area close). The Comptroller issues a proclamation authorizing the emergency closing in accordance with 12 U.S.C. 95 at the time of the emergency condition, or soon thereafter. When the Comptroller, a State, or a legally authorized State official declares a legal holiday due to emergency conditions, a national bank may temporarily limit or suspend operations at its affected offices. Alternatively, the national bank may continue its operations unless the Comptroller by written order directs otherwise.
(c) Ceremonial closings. A state or a legally authorized state official may declare a day a legal holiday for ceremonial reasons. When a state or a legally authorized state official declares a day to be a legal holiday for ceremonial reasons, a national bank may choose to remain open or to close.
(d) Liability. A national bank should assure that all liabilities or other obligations under the applicable law due to the bank's closing are satisfied.