41 million Americans under hard freeze warnings Tuesday: What does that mean?

Cold weather gripped the country this MLK Day weekend.

In Iowa, voters experienced the coldest Caucus Day on record. The NFL postponed a game and Buffalo Bills fans helped shovel the stadium out from inches of snow.

And in the Southeast, where the climate is usually more temperate, millions are dealing with frigid weather.

More than 41 million people were under hard freeze warnings Tuesday morning. The warnings stretched from Texas into Louisiana to parts of northern Florida as the Southeast bundles up for the cold.

Here is what to know about hard freeze warnings, where the warnings are in effect and how to stay safe.

A freeze warning warns residents at an apartment complex to let their faucets drip and keep heat on during a winter storm on Thursday, Feb. 3, 2022.

See photos:Winter weather bringing freezing temperatures across the US

What is a hard freeze warning? How is it different from a freeze warning?

The National Weather Service issues a variety of warnings related to cold weather, including wind chill watches and warnings, as well as freeze watches, warnings and advisories.

A hard freeze warning is issued when temperatures are forecasted to drop below 28 degrees for an extended length of time.

A freeze warning is issued when it is a bit warmer, going into effect when temperatures below 32 degrees are expected for a long period of time.

A freeze watch is when there is a potential for widespread freezing in 24 to 36 hours.

A frost advisory is issued when frost is expected or occurring.

Freeze warnings in effect Tuesday

  • Alabama - Hard freeze warnings in effect in certain areas
  • Arkansas - Hard freeze warnings in effect
  • Florida - Hard freeze warnings, freeze warnings and freeze watches in effect
  • Georgia - Hard freeze warnings in effect
  • Louisiana - Hard freeze warnings and freeze warnings in effect
  • Mississippi - Hard freeze warnings and freeze warnings in effect
  • Oklahoma - Hard freeze warnings in effect
  • Texas - Hard freeze warnings and freeze warnings in effect

Pipes, plants at risk during hard freeze warnings

The NWS says even frost can affect vegetation sensitive to the cold, and commercial crops and plants are at risk of being killed under a hard freeze warning.

"Take steps now to protect tender plants from the cold," the NWS said in its latest weather advisory about hard freeze warnings.

Also at risk of damage are outdoor water pipes and in-ground sprinkler systems, NWS notes. You can drain the pipes or, if they are above ground, wrap them to keep them from freezing.

But humans can also be at risk in extremely cold weather.

Stay safe: avoid frostbite and hypothermia

Humans in cold weather can become at risk of frostbite or hypothermia.

NWS describes frostbite as a survival mechanism, during which your body cuts of circulation to extremities to conserve heat for the vital organs. At first the skin may feel painful or become red. Other signs of frostbite include white or gray-yellow skin, numbness or unusually firm or waxy skin.

To avoid frostbite, stay inside and cover all areas of your body when you must go out. Avoiding wind can also help.

Hypothermia happens when your body temperature dips below 95 degrees. If that happens to you or you feel cold and sluggish, the NWS suggests seeking medical attention immediately.

To avoid hypothermia, dress in layers, eat nutritious and warm food, and ask your doctor if any medication you're taking could increase the risk of hypothermia.

Contributing: Bianca Harris, USA TODAY