MADISON, Wis.— The temperatures are going to continue to tumble throughout the entire weekend. Air this cold can turn dangerous in a matter of minutes. 

Even if it looks pretty, winter days like this can be painful, and even harmful. In sub-zero temperatures, it can take just minutes for frostbite to set in. 

“It takes real intentional planning to make sure that you don't get yourself in trouble,” said Dr. Jeff Pothof, UW Health’s Chief Quality Officer. 

Your first line of defense is how you dress. You should be covering as much skin as possible. 

“You want to dress in layers, you want that base layer, a mid-layer, and then some sort of outerwear,” Pothof said. “That allows you to trap more heat.” 

We all know that feeling when your ears start to go numb. That’s a normal part of the Wisconsin winter. But in arctic air, that feeling should be your first sense of alarm bells. 

“Your fingers or your toes or your nose or ears, they're going to go numb, or you're going to lose some of that sensation,” Pothof said. “That's an early warning sign.” 

He said in weather this cold, that’s when you should go inside.

If you push past that numbness, things can start to get dicey. 

“The next thing you'll see is they'll start to get pale, they'll lose that pink rosy color, and they'll start to look a little bit more white, or bluish. That's a much more severe sign,” Pothof said. “After that, you might even start seeing things like blisters and things like that start to develop, which is just too late.”

Frostbite can quickly cause permanent damage. 

“Frostbite is really those tissues freezing, and then you can imagine that there's ice crystals in those tissues, and that can be very damaging to the tissues,” he said. 

When it’s time to come inside and warm up, there are specific ways to do it safely. Your first instinct might be to rub your hands together or use hot water to warm up. Pothof said neither of those is a good option. 

“You can just do passive warming, that might be sticking your fingers in your armpit and letting them warm up that way,” Pothof said. “You can use very lukewarm water, that's an effective way to start warming things back up.” 

He said you should avoid coming in for a few minutes to warm up a little, and going back out. He said that can do more bad than good. 

The best thing you can do is stay inside as much as possible. 

“Consciously think about, ‘What am I going to do this weekend? And am I taking the appropriate precautions to stay safe?’” 

If you have lingering pain, swelling, redness or discharge in an area that got too cold, it’s time to see a doctor.