Wednesday was Baltimore's coldest day since last March, and Thursday could be even colder, prompting several school districts in the state to delay opening Thursday morning.
Temperatures spent the day in the teens and lower 20s, with a high of 24 degrees at Baltimore-Washington International Thurgood Marshall Airport in the late morning and a low of 14 in the early morning, though it was possible temperatures could drop lower late Wednesday night.
Thursday, temperatures are forecast to stay between the upper teens and lower 20s all day, with blustery winds making it feel like the single digits.
Anne Arundel, Baltimore City, Harford and Prince George's County officials said Wednesday afternoon that schools there would open two hours late Thursday morning, joining districts across the state and the Midwest that closed or delayed schools Wednesday because of Arctic air surging south.
In Baltimore, officials worked to urge homeless people to seek warmth in shelters that opened up more than 200 extra beds overnight, with wind chills expected to drop overnight to zero or below.
Though not as extreme as last winter's outbreaks of frigid weather, the column of cold air known as the polar vortex is expected to bring below-normal temperatures into early next week — along with the possibility of more wintry precipitation.
The frigid weather challenged cleanup from Tuesday's light yet treacherous snow. Schools in Anne Arundel, Baltimore, Howard and Harford counties opened two hours late Wednesday because of icy conditions.
By Wednesday night, though, attention turned to a dangerously cold wind chill. The National Weather Service issued an advisory from 10 p.m. Wednesday through 8 a.m. Thursday warning of wind chills as cold as 10 degrees below zero.
Teams from homeless shelters and community organizations were combing Baltimore streets for homeless people Wednesday, urging them to seek shelter overnight, said Olivia Farrow, director of the mayor's office of human services. City health officials declared a "Code Blue" alert Wednesday through Friday, a designation that expands city homeless shelters' capacity from about 1,100 to 1,350 beds, Farrow said.
Outreach teams ask the homeless people if they have a warm place they're trying to get to, or if they would agree to stay in a city shelter for the night. But they can't force anyone to go to a shelter.
"Sometimes it's just as simple as arranging a ride to a family member's home across town, which preserves important shelter space," said Gabby Knighton, housing policy coordinator with the office's homeless services program.
Across the country, the Arctic air is prompting efforts to protect vulnerable populations from the cold. With temperatures close to or below zero and wind chills well below that, school districts across the Upper Midwest closed or delayed openings. In northern Illinois, more than 200 school districts closed Wednesday as temperatures hovered around zero at daybreak and dangerous wind chills were forecast for the rest of the week.
In Iowa, schools were delayed Wednesday because buses can't run below temperatures of 15 degrees below zero, and temperatures were forecast to drop as low as 20 below.
The lowest temperature recorded in the contiguous United States was 30 degrees below zero near Poplar, Mont.
The cold is forecast to last into next week. Temperatures are expected to rise to a few degrees above freezing Friday afternoon, but otherwise should stay in the teens and 20s until hitting the 30s again Sunday.
Though the temperatures are 10 to 15 degrees below normal, they are not expected to threaten any records.
Forecasters are now looking at chances for a wintry mix or snow Monday.
Tribune Content Agency contributed to this article.