12 December 2024

We won’t have frost on our eyelashes but today it will feel like we ought to. Pittsburgh’s current temperature of 21°F is only half of the normal high (42°F), and the wind chill in 15-24 mph wind makes it feel much worse.

The wind chill temperature is how cold people and animals feel when outside. Wind chill is based on the rate of heat loss from exposed skin caused by wind and cold. As the wind increases, it draws heat from the body, driving down skin temperature and eventually the internal body temperature.

— National Weather Service (NWS): Understanding Wind Chill

This wind chill chart shows how temperature and wind create a “Feels Like” temperature. Blue-to-purple background colors indicate how quickly exposed skin gets frostbite. Under extreme conditions it can take only 5 minutes. (I have circled today’s approximate values in red.)

Yes, it feels cold and to make matters worse our bodies are not used to it. Just two days ago it was partly sunny and 59°F on Monday afternoon, 10 December.

So bundle up. It is wind chill-y today.

p.s. How cold does it have to be to get frost on your eyelashes? Minus 50°F == -50°F.