We lose heat through convection. However, with little to no wind, a layer of that heat remains to help us stay warmer. No wind, 20-degrees, it feels like 20.
When it’s windy, the moving air breaks up the insulating warm layer. This helps to speed up heat loss, making it feel much colder.
So a 20 mile-an-hour wind with a temperature of 20 makes it feel like 4-degrees.
There’s a winter safety tip for wind chills like that.
Dress for conditions, limit time outside, check on others and watch for icy areas.
For your home, check the furnace, chimneys, monoxide detector and insulate exposed pipes.
For your car: check the battery, tire pressures, have jumper cables and a blanket in the trunk.
Bring the pets inside or provide an outside shelter, provide fresh water and keep salt away from paws.

Wind Chill calculator

Wind Chill safety