On Thursday morning, D.C. area commuters face bitter cold temperatures, late openings for some schools and possible icy spots along roads.

There were no reports of serious crashes on the big commuter routes in the Washington area. Transportation and police officials reminded commuters to allow extra time and to use caution. Temperatures in Dupont Circle at 5:30 a.m. were at 8 degrees. And in Leesburg, Va., it was 1 degree.

Some schools are closed or delaying their openings due to weather concerns.

The extremely cold weather over the last few days has led to delays on roadways, trains and planes. On Thursday, more than 2,400 flights were either canceled or delayed in the United States, according to FlightAware.com. And at the D.C. region’s three airports, more than 60 flights were impacted.

Officials are worried that there may still be some slick spots on area roads, and with the extremely cold overnight temperatures, any slush or snow may have refrozen.

The Virginia Department of Transportation said trucks were out in Northern Virginia overnight and into the early morning treating area roadways.

Throughout the region, drivers have had to deal with potholes earlier than normal after heavy rains over the last few months. On Thursday, crews were working to fix a large pothole along the Capital Beltway’s inner loop near St. Barnabas Road in the Oxon Hill area.

As for trains, there are some delays on two Metro rail lines and on the MARC commuter train’s Penn Line.

The polar vortex is bringing extreme cold to the region and to roughly 90 million people across the country. It has left six people dead in Michigan, Wisconsin and Minnesota. The fatalities included several people who froze to death.

A man rides Capital Bikeshare bicycle Wednesday morning in downtown Washington, D.C. (Andrew Heining/The Washington Post)

Farther north, parts of western New York are getting hit hard with lake-effect snow, according to The Washington Post’s Capital Weather Gang. In some spots, temperatures fell to nearly 50 degrees below zero, and power outages hit large parts of Wisconsin and Iowa.

In the D.C. region, the CWG said Thursday was the “coldest morning of the winter so far!” Lows at Reagan National Airport were 10 degrees. At BWI airport, the temperature was 6 degrees, and Dulles Airport came in at minus-2. But with wind chills, it feels around minus-5.

Forecasters said locals should expect “bitter Arctic air” on Thursday and possible snow showers Friday. But by Saturday, temperatures are expected to rise to more normal, seasonal levels. And by next week, temperatures in the Washington area could hit 60 degrees.