Unusual heat wave hits Chicago

Why it matters: Unusually high temperatures are sweeping across the U.S. and could lead to more severe weather.

And when you need the real scoop on Chicago weather, we all know there is one trusted source to turn to.

• "Our observational record goes back 150 years. If we achieved the 66 degree reading, we would break a 70 year-old record," WGN-TV meteorologist Tom Skilling tells Axios. "Our winters are running four degrees warmer than they were as recently as the 1970s.
• "One in four Decembers on average has produced a 60 degree day."

The big picture: It's great to have a nice day in December, but winter warm-ups cause several problems, including severe weather.

• "The tornado system that just came through Southern Illinois and Kentucky was historic," Skilling says. "We also had a tornado touch down in Crown Point, Indiana. It was the first December tornado to ever hit the Chicago area."

Go deeper: Axios' Andrew Freedman crunched the data to show how Friday's tornadoes were powered by climate change. The research begs the question: should Chicago be worried about severe weather this week?

• "This storm out West is a giant wind machine," Skilling says. "We may see 50 to 60 mile an hour winds in Chicago tonight or tomorrow morning."

What's next: When asked about the potential for holiday snow, Skilling says, "Unless it's out there and we haven't seen it yet, the chances for snow on or before Christmas are looking a little anemic."