Another brutal week of dangerous heat is bearing down on the United States, and this time the nights aren’t offering much of a break either.
The National Weather Service is forecasting that more than 90 temperature records across the country could be tied or shattered by Wednesday — and the majority of those records are expected to fall overnight, not during the day.
Health professionals warn that high nighttime temperatures are actually more hazardous than scorching daytime highs, because the body never gets the chance to recover.
A long-lasting heat dome has been smothering much of the country, making this one of the hottest starts to summer in recent memory. The extreme temperatures in recent weeks have already been linked to heat-related deaths in New Jersey and have contributed to wildfire activity in the West.
In cities like Fort Lauderdale, Florida; Miami; Tampa, Florida; Galveston, Texas; and Charleston, South Carolina, nighttime temperatures are not expected to dip below 80 degrees Fahrenheit (27 C), according to the National Weather Service.
Even areas of the Midwest and Northeast more commonly associated with harsh winters will see nighttime temperatures stay above 70 degrees Fahrenheit (21 C) over the next several days — including Fargo, North Dakota; International Falls, Minnesota; and Portland, Maine.
The reason overnight heat is so dangerous comes down to basic biology: when temperatures stay high through the night, the body’s core temperature never gets a chance to cool down and reset from the strain of the day.
“That’s where the health outcomes are amplified, particularly for the elderly and vulnerable communities,” explained University of Georgia meteorology professor Marshall Shepherd.
Even a small rise in core body temperature can trigger heatstroke or put dangerous levels of stress on the heart.
Kristie Ebi, a public health and climate scientist at the University of Washington, noted that when nighttime temperatures fail to bring relief, the health consequences often don’t show up until the following day. “Mortality starts the second or third day” because the body is simply unable to cool itself down, she said Monday.
Early warning signs of heat illness include heavy sweating, muscle cramps, and headaches. “It’s hard to know you’re getting in trouble with the heat. This is why we need to be more proactive,” Ebi said.
Cooling down is essential — whether that means stepping into an air-conditioned space or simply wrapping a cold, wet towel around your neck.
Health experts are also urging people to check in on friends and family, particularly those who are elderly, pregnant, or dealing with health conditions that make it harder to cope with extreme heat.
Even for those without air conditioning at home, options are available. Heading to a library or a shopping mall can provide relief. Sitting in front of a fan while misting your skin with water, soaking your feet in cold water, wetting your clothing, and staying well-hydrated are all practical steps that can make a real difference.
