Monday began with a dense-fog advisory for the Triangle, and the day's forecast was like a windshield wiper sweeping one way as a warm front crossed the area and then back with frigid air overnight.
The National Weather Service issued the fog alert through 9 a.m. and urged drivers to be especially cautious around schools and bus stops because of the reduced visibility.
Highs Monday promised to be from the mid-60s to the low 70s, west to east, across the Triangle, powered by warm air from the Gulf of Mexico.
By nighttime, a cold front from the northwest was forecast to take over, and below-freezing lows were slated for Monday night and the rest of the week.
Rain was a strong probability Monday, and thunderstorms were possible, forecasters said, but rain totals of a half-inch or less were expected.
Highs during the week should start around 40 degrees on Tuesday and get into the mid-50s by Friday