A widespread frost is forecast across the Baltimore region early Saturday, and a hard freeze could follow Sunday morning.
The National Weather Service has issued a frost advisory from 1 a.m. to 9 a.m. Saturday. Lows are forecast in the lower to mid-30s along the Interstate 95 corridor, and around or below freezing to the north and west.
The frost advisory is in effect for Anne Arundel County, Baltimore City, southern Baltimore and Harford counties and the eastern half of Howard County. In the rest of the region, in suburbs at higher elevations north and west of the city, freezes have already ended the growing season, so no more advisories will be issued this season.
Then, early Sunday morning, a freeze watch is in effect for those same areas where the growing season is ongoing. Lows are expected in the upper 20s to lower 30s.
Temperatures very briefly hit 30 degrees early Tuesday at Baltimore/Washington International Thurgood Marshall Airport, according to weather service observations. But hourly readings at the airport and at other weather stations around the region showed temperatures were otherwise mostly above freezing that morning.
Before that, the last sub-freezing temperatures at BWI came April 10.
Baltimore has a 50/50 chance of experiencing its first freeze by Nov. 13, according to the University of Maryland Extension. Two out of every three years, it comes by Nov. 18.