The answer depends on whether the employees are exempt or nonexempt under the Fair Labor Standards Act. Exempt employees must still be paid when you close due to inclement weather. Nonexempt employees, however, only need to be paid for actual hours worked, plus any reporting time pay that may be required by state law.
That said, you should also be consistent with your own policy and practice. If you have been paying all employees—regardless of their employment classification—for hours they would have worked had you not closed for bad weather, then you should continue to do so. If you would like to end that practice, we recommend creating a clear written policy and distributing it to all employees prior to implementation.