?? 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.