Nearly 5,000 flights have been canceled nationwide Friday, according to FlightAware.

There are nearly 800 cancellations for Saturday.

Amid the ground stop, United Airlines said it plans to cancel the majority of its remaining flights for the night, with exceptions for some international flights.

JetBlue said it is also canceling all remaining flights on Friday, save for Europe-bound flights departing from JFK and Boston.

"Flights already in the air are continuing to their destinations," JetBlue said in a statement. "We expect disruptions to continue into tomorrow, including additional cancellations."

The Big 12 Conference said Friday it is "evaluating any potential changes to Saturday's football schedule" due to the national ground stop.

"The Conference will continue to monitor the travel disruptions alongside its member institutions and provide updates for Saturday's games," the college athletic conference said in a statement.

A small number of flights are taking off over the ocean and in Alaska and Hawaii.

Alaska and Hawaiian Airlines said in a statement that flights within Hawaii and from the West Coast to Hawaii can continue. International flights from Hawaii are also cleared. 

Hawaii's Department of Transportation said that flights between Anchorage to Oakland and Hawaii can fly.

San Francisco International Airport said that Pacific-bound flights are cleared to depart from the airport, including to destinations in Alaska and Hawaii.

Ontario Airport in California said that flights heading west over the ocean are allowed to take off from the airport at this time. 

Boston Logan said in a post that the FAA is permitting some transatlantic flights to depart.

-ABC News' Bonnie McClean