'Life-threatening wind chills' impacts millions this weekend 01:42 (CNN)Americans in the northern United States who venture outside unprotected this weekend face the risk of frostbite and hypothermia amid bitter cold temperatures and dangerous wind chills. Temperatures across the Midwest, Plains and Mountain West will range from 20 to 40 degrees below normal over the next five to seven days. Factor in wind gusts of 20 to 30 mph, and there will be life-threatening wind chills as low as 50 degrees below zero. "Wind chills as low as -50 degrees could cause frostbite on exposed skin in as little as 10 minutes," said the National Weather Service Office in Bismarck, North Dakota. "Frostbite and hypothermia are likely if proper precautions are not taken when outdoors."