PHILADELPHIA (WPVI) --Temperatures in the 20s on Friday didn't stop many runners, walkers or pets along Kelly Drive, but most were wearing several layers to keep warm.
"I've got everything, hats, gloves, I'm good," said John Krajewski of Fairmount.
And his German Sheppard "Pepper" didn't stay out long.
But Dr. David Targan says even greater precautions are needed this weekend as temperatures plunge.
"You need to watch out for two main things and the main things you need to look for are frostbite and hypothermia," said Dr. Targan.
You lose the most body heat from your head and torso, but smaller areas typically suffer frostbite first.
"Such as fingertips and your ears so you really need to be aware and cognizant that you need to cover everything up this weekend," said Dr. Targan.
As for avid exercisers, Joel Rodriguez of Media says, "When you're running I think it feels about 20 degrees warmer than what actually the temperature is."
Moving will help keep your body warm, but sweating can increase the risk for frostbite.
Dr. Targan says if you're skiing this weekend, take lots of breaks.
As for runners, he recommends moving your workout inside.
"That's why we invented treadmills and a gym," said Dr. Targan.
Early signs of frostbite include numbness, tingling and skin turning red, white or grayish, or appearing waxy-looking.
One runner we spoke to assured us her hands were covered earlier and she'll cover them up again.
As for hypothermia, that's when your body temperature dips below 95 degrees.
Signs such as shivering or confusion mean you need to go inside, somewhere warm and dry.