Much of the United States is bracing for another week of intense heat as a persistent heat dome shows no signs of dissipating, increasing health risks across the country. The National Weather Service predicts that more than 90 temperature records could be tied or broken through Wednesday, with a significant number of these anticipated overnight heat records.

Health experts emphasize that high overnight temperatures, which prevent the body from cooling down, pose a greater danger than daytime highs. "That's where the health outcomes are amplified, particularly for the elderly and vulnerable communities," said Marshall Shepherd, a meteorology professor at the University of Georgia. Just a few degrees of increased body temperature can lead to heatstroke or put excessive strain on the heart.

Kristie Ebi, a public health and climate scientist at the University of Washington, noted that the health impacts can become more severe on the second or third day of a heatwave if the body cannot recover. "Mortality starts the second or third day" due to the body's inability to cool, she stated.

Early warning signs of heat-related 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 advised. She recommends seeking air-conditioned spaces, using cool towels, and staying hydrated. Checking on vulnerable friends and family members, particularly the elderly, pregnant individuals, or those with pre-existing health conditions, is also crucial.

For those without air conditioning, strategies to beat the heat include visiting public places like libraries or malls, sitting in front of a fan with a water spray, immersing feet in cold water, soaking clothes in water, and drinking plenty of fluids. Communities in the Midwest and Northeast, typically known for colder winters, are experiencing nighttime temperatures remaining above 70 degrees Fahrenheit (21 Celsius), with cities like Fargo, North Dakota, and International Falls, Minnesota, among those affected. Coastal areas such as Fort Lauderdale, Miami, Tampa, Florida, Galveston, Texas, and Charleston, South Carolina, are not expected to see nighttime temperatures drop below 80 F (27 C).

The prolonged heatwave has already contributed to heat-related fatalities in New Jersey and fueled wildfires in the western United States.