DENVER – Football fans, and everyone else who plans to be outside this weekend, should plan to bundle up.

Friday’s weather felt like fall, with sunny skies and mild temperatures.

It was warm enough for Eric Crilley and his buddy Hunter McClung to wear short- sleeves while they played catch outside of Canvas Stadium in Fort Collins.

“Especially before it gets cold,” Crilley said. “I don’t know when we’re going to have playing weather like this again.”

They might have to wait for while, because winter-like weather will come roaring in Saturday during the middle of the Rams game.

And if fans aren’t prepared, they could be left feeling cold and foolish.

“I’ll be prepared, I’ll bring some coats,” McClung said.

Fans will need those coats and more come Sunday at the Broncos game.

Temperatures are expected to be in the 20’s for the entire game.

That’s dangerously cold, said Dr. Anne Wagner, the medical director at the UCHealth University of Colorado Hospital Burn Center.

“Wear lots of layers. Dress in layers. Wear as much orange and blue as you can,” she told FOX31.

Dr. Wagner also recommended using a plastic poncho to stay dry. It can also keep you warmer.

“Be careful about how much alcohol you’re using. Alcohol can make you not realize that you’re getting as cold as you are,” she added.