S.D. Codified Laws § 51A-4-18
In the event of a legal holiday, power failure, fire, act of God, riot, strike, robbery or attempted robbery, epidemic, interruption of communication facilities, or for such other reason as the director may determine to be good cause, or in the event of the declaration of the existence of an emergency by the Governor or such other person lawfully exercising the power and duties of the office of Governor, a bank, in the reasonable and proper exercise of its discretion, may determine not to open its main office or any branch on any business or banking day, or, if having opened, to close such main office or any branch during the continuation of any such occurrence or emergency.
Except for legal holidays, the bank shall, as soon as practicable, notify the director of the nonopening or closing period. In no case may the bank be required to comply with any other provision of law regarding the closing or reopening of banks or financial institutions. Any act, which could not be executed because of the closing, may be performed on the next succeeding business day that the main office or branch is reopened for business. Any other provision or rule of law notwithstanding, no liability or loss of rights of any kind on the part of any person, firm, or corporation, or of such bank, may accrue or result by virtue of the nonopening or closing.
In the event of an emergency or natural disaster affecting a bank's community, a bank may, without notice or advance permission from the director, temporarily extend its banking hours for the public convenience during the term of the emergency and disaster. In the event of an emergency or natural disaster, the director may waive any provision under this Title to provide for the continued access to banking facilities by the citizens of this state.
The right of a bank not to open or close under this section and the protections afforded with respect thereto are in addition to and not in lieu of any rights or protections granted under § 57A-4-108.
SDCL 51A-4-18