What wind chill means
On a still winter morning, your body warms a thin layer of air right next to your skin. Wind strips that layer away, and you lose heat faster. That is the idea behind wind chill. The National Weather Service describes it as how cold it feels to people and animals outdoors, based on the rate of heat loss from exposed skin caused by wind and cold.
The wind chill index the NWS uses today took effect on November 1, 2001. It was built to estimate what the wind does at about 5 feet off the ground, the typical height of an adult face. Scientists from universities and the U.S. and Canadian governments helped develop it.
One thing wind chill does not do: it doesn’t make the air itself any colder. Your car radiator or a water pipe can’t drop below the actual air temperature, no matter how hard the wind blows. Wind just cools them to that temperature faster. Wind chill is about people and animals.
Reading the chart: how fast frostbite can happen
The NWS wind chill chart lists air temperature across the top and wind speed down the side. Where they meet is the wind chill. The chart is shaded to show how long it can take for exposed skin to get frostbite: about 30 minutes, 10 minutes or 5 minutes.
Two examples help. At 0 degrees with a 15 mph wind, the wind chill is 19 below zero, and exposed skin can freeze in about 30 minutes. At 10 below with a 30 mph wind, the chart lands near 40 below, and frostbite can set in in about 10 minutes.
Our storm patterns pages explain lake-effect snow and the other winter setups that bring cold, windy days to La Porte County. Keep the chart in mind on those days. A day that is “only” in the single digits can still be dangerous for a kid waiting at the bus stop without a hat.
The NWS alerts: new names since 2024
If you remember Wind Chill Advisories and Wind Chill Warnings, those names are gone. Around October 1, 2024, the NWS renamed and combined its cold alerts:
- Cold Weather Advisory replaced the Wind Chill Advisory.
- Extreme Cold Watch replaced the Wind Chill Watch.
- Extreme Cold Warning replaced the Wind Chill Warning.
The Hard Freeze Watch and Hard Freeze Warning were folded into the Freeze Watch and Freeze Warning at the same time. The new alerts can be issued for dangerous wind chills or for very cold air temperatures, even when the wind is light. Cold can be dangerous without any wind at all.
The exact thresholds are set by each local NWS office. La Porte County is served by NWS Northern Indiana, so its alerts are the ones that count here. This page is not a forecast; check our emergency page for official alerts in effect now.
Know the warning signs
Frostbite most often hits the nose, ears, cheeks, chin, fingers and toes. Watch for numbness and for skin that changes color and turns hard or waxy. Because the skin goes numb, it is easy to miss. Get out of the cold and seek medical care. Don’t rub the area. Rewarm it gently in warm, not hot, water, and don’t use a heating pad, heat lamp, stove or fireplace, because numb skin burns easily.
Hypothermia is a body temperature that has dropped too low. Warning signs include shivering, exhaustion, confusion, memory loss, slurred speech and drowsiness. A body temperature below 95 degrees is a medical emergency. Call 911, get the person somewhere warm and remove wet clothing.
Dressing for wind chill
- Wear several loose layers. Make the outer layer water-resistant, with a hood if you can.
- Cover your head and face. A hat, plus a scarf or knit mask over the face and mouth.
- Cover your hands. Mittens or warm gloves, and keep a spare dry pair in the car.
- Keep dry. Wet clothes and wet boots pull heat away fast. Change out of them when you come in.
- Limit time outside when the wind chill is low, and check on older neighbors and anyone without good heat.
Pets feel it too
Pets left outside in bitter cold can get frostbite or hypothermia. The American Veterinary Medical Association and the Red Cross both recommend bringing pets indoors in cold weather. Keep walks short on bitter days, and wipe paws, legs and bellies afterward to remove ice melt and other chemicals. Clean up antifreeze spills right away. Before starting your car, bang on the hood and honk, because cats sometimes crawl under it for warmth. And never leave a pet alone in a cold car.
Animals that must stay outside, including livestock, need a dry, draft-free shelter out of the wind and water that isn’t frozen. If you think a pet has frostbite or hypothermia, bring it inside and call your veterinarian.
Questions
Does the NWS still issue Wind Chill Warnings?
No. Since about October 1, 2024, the Wind Chill Advisory is a Cold Weather Advisory, the Wind Chill Watch is an Extreme Cold Watch, and the Wind Chill Warning is an Extreme Cold Warning.
How fast can frostbite happen?
The NWS chart shows zones of about 30, 10 and 5 minutes. At 0 degrees with a 15 mph wind, the wind chill is 19 below and exposed skin can freeze in about 30 minutes.
Can wind chill freeze my car or pipes faster than the air temperature?
Wind cools objects to the air temperature faster, but it can’t take them below it. Wind chill applies to people and animals.
Where do I find cold alerts for La Porte County?
La Porte County is served by NWS Northern Indiana. Our emergency page lists official alerts in effect.
Sources: NWS: Wind chill chart · NWS: Wind chill brochure · NWS Service Change Notice 23-44: freeze and cold products · Star Tribune: National Weather Service changes cold weather alerts · CBS News: How cold is it really? (2001) · CDC: Preventing frostbite · CDC: Preventing hypothermia · AVMA: Cold weather animal safety