?? Orlando International Airport was forced to ground all flights Sunday afternoon after “extreme cold” sparked an emergency at the air traffic control tower.

The FAA initially issued a ground stop due to a “possible fire,” but the order was lifted at 4:15 p.m. once the cause was identified.

In the end, officials confirmed that the unusually cold temperatures — around 43°F — triggered a sprinkler head in the tower’s fire suppression system, setting off the alarm and halting operations.