The coldest weather since last winter blew in Monday and was forecast to bring single-digit wind chills overnight and keep temperatures below freezing throughout Tuesday.
Lows are forecast in the mid-teens early Tuesday morning, but, with a cold north wind gusting up to 30 mph, it could feel 10-15 degrees colder.
Baltimore Health Commissioner Leana Wen issued a "Code Blue" advisory, urging vulnerable and homeless residents be sheltered or face risks of hypothermia and other cold-weather-related illnesses.
Temperatures might not rise above the freezing mark Tuesday afternoon. Highs are forecast in the low 30s, about 10 degrees below normal for this time of year, under sunny skies. A 10-15 mph wind is forecast to make it feel like the 20s all day.
More bitter cold is forecast early Wednesday morning, with lows again falling into the mid- to upper teens. But winds are expected to calm by late Tuesday night, making it feel slightly less frigid.
Temperatures topped out at 37 degrees Monday afternoon at Baltimore/Washington International Thurgood Marshall Airport, the region's point of record. That made it the coldest day there since March 6, which had a high of 28 degrees, according to National Weather Service data.
Though some flurries were reported around the region Monday, no snow fell at BWI, according to the weather service.