Mont. Code Ann. § 32-1-562

When the department is of the opinion that an emergency exists or is impending in this state or in any part of this state, it may, by proclamation, authorize banks located in the affected area to close any of their offices. In addition, if the department is of the opinion that an emergency exists or is impending which affects or may affect a particular bank or banks, or a particular office or offices thereof, but not banks located in the area generally, it may authorize the particular bank or banks or office or offices so affected to close. The office or offices so closed shall remain closed until the department proclaims that the emergency has ended or until such earlier time as the officers of the bank determine that one or more offices theretofore closed because of the emergency should reopen and, in either event, for such further time thereafter as may reasonably be required to reopen.