Fallin made the declaration Monday. The declaration gives the state a mechanism to allow local governments to be reimbursed for costs related to the storm.
The order also is a first step toward seeking federal aid if such aid is necessary.
The National Weather Service has issued a winter storm warning for much of the state that will be in effect from 6 p.m. Monday until 6 p.m. Tuesday. Forecasters are predicting the storm will bring as much as a foot of snow to parts of Oklahoma along with bitterly cold temperatures.