Cold And Heat: Which Is More Dangerous, And Why?

Extreme cold and heat can be deadly, but which is more deadly often depends on where you live, how you can protect yourself and how healthy you are.
Posted at 5:30 PM, Jan 30, 2019

When you're in the middle of a cold snap that freezes the pipes or a heat wave that melts the pavement, it can be hard to think anything is worse. But which really is worse? The heat or the cold? 

"Heat is our No. 1 weather-related killer in the U.S.," said Greg Hanson, a warning coordination meteorologist with the National Weather Service. "That's above floods, tornadoes, hurricanes, everything. It's about four times more deadly than extreme cold."

As a bottom line, that's pretty conclusive. But weather experts say the exact risk of the different extremes depends on a lot of factors. One of them is time. Cold gets dangerous faster than heat does.

"If you go out in it at that moment, it's probably more dangerous than the heat," Hanson told Newsy. "It's a hot day, but it's not going to kill you right away. Where the cold, if you're out in 20 minutes without the right covering you become hypothermic. … The heat is very much an accumulating thing."

Other factors include where you live, what resources you have to protect yourself and, critically, how healthy you are.

Cold can be especially deadly when it complicates other health problems. A 2015 study in The Lancet analyzed more than 74 million deaths across five continents, mostly in urban areas. It found cold was some 17 times more deadly than heat, in part because the cardiovascular problems cold caused lasted longer.

But heat is persistent. It doesn't let up the same way a cold snap does. It soaks into our cities and raises temperatures both day and night. That can make it harder to escape.

"The heat impacts vulnerable populations a lot more," Hanson said. "People that don't have air conditioning, very poor, can't get to a place to be cool, can't cool off. It really impacts the people who just aren't equipped to handle it."

Some research suggests cold deaths will drop off as average temperatures climb. For those who have it, air conditioning can lower the risk of heat deaths. But scientists are somewhat confident that heat mortality is already becoming more of a problem.

"The colder areas and the colder times of day are where we see the biggest change in temperature," Hanson said. "We're setting a lot more record-high minimum temperatures than we're setting record daytime highs. … There's no question we're getting warmer."