The National Weather Service says to stay cautious when roads look wet in the winter.
PHILADELPHIA (WPVI) -- When temperatures fall rapidly, anything wet on the ground will freeze.
This is known as a flash freeze. The National Weather Service calls it a "sneaky" winter hazard.
Wet roads can freeze quickly at night or when there is a rapid drop in temperature behind a cold front, the NWS explains.
"Even when it's not precipitating, wet roads can quickly turn icy as temperatures dip below freezing," the NWS says. "These unexpected slippery conditions can make driving hazardous."
The NWS says to stay cautious when roads look wet in the winter.
They say to slow down your vehicle and don't use cruise control.
A flash freeze is not freezing rain; it's when standing water freezes.
This can cause icy trouble for any untreated surfaces.
Bridges have a better chance of icing because they lose heat from the top, side and bottom. They are often made of steel and are a good conductor of energy.
A flash freeze could also lead to car doors being frozen shut if they are wet.
Once precipitation passes, you can always throw some salt onto your steps and sidewalk to prevent icy conditions on those surfaces. Just be careful when going outside.
As the NWS says, "Don't let flash freezes sneak up on you!"