Jason Michaud stays hydrated while sunning himself in Portland's Monument Square on Monday. Weather forecasters are predicting hot weather all week. Credit: Troy R. Bennett / BDN

During the hottest week of July, 64 Mainers visited the emergency room for heat-related conditions.

That was 11 people more than the hottest week last year, according to the Maine Tracking Network. The temperature peaked on July 6 at 92.2 degrees, causing 27 people on that day alone to head for emergency rooms here with symptoms including high body temperature, heat exhaustion and cramps.

Unofficially, it was the hottest day on record this summer, according to the University of Maine. Visits to ERs, per 100,000 population, were higher in Maine that day than in most of the rest of the country, according to the U.S. Centers for Disease Control Heat & Health Tracker.

More heat days and hospital visits is a growing trend across the country as the climate and oceans warm, even in cooler states like Maine.

Particularly at risk are elderly and homeless people along with those who have underlying health conditions. The hot days may not yet be over this summer. At the end of last August, temperatures reached the high 80s and 16 people visited ERs because of the heat.

Beachgoers play in the surf, Sept. 4, 2020, at Old Orchard Beach. Several cities across New England recorded their hottest summers on record, a period marked by dry weather, a drought in some locations, and hundreds of forest fires in the region. Credit: Robert F. Bukaty / AP

Mainers are not as accustomed to the heat as people in other parts of the country. They can take some precautions to cool off during high heat days.

The Maine Emergency Management Agency recommends staying indoors as much as possible and remaining on the lowest floor of your home and out of the sunshine if you don’t have air conditioning. Go to a cooling center or public building such as a library during the hottest part of the day. Drink water and limit alcohol and caffeinated beverages that cause you to lose body fluid. Have someone to contact in case of emergency.

Around the house, install a window air conditioner or temporary window reflectors such as aluminum foil-covered cardboard to reflect the heat back outside. Pull drapes shut on windows that get morning or afternoon sun, and consider keeping storm windows installed year-round.

Heat-related ER visits are expected to keep climbing in the future, because extreme heat is a consequence of climate change, said Alice Hill, senior fellow for energy and the environment at the Council on Foreign Relations, a national think tank. Coupled with humidity, the outside temperature can feel much hotter and cause more illness. Nighttime temperatures tend not to drop as much during heat spells.

All Maine counties are predicted to see the number of days topping 90 degrees double over the next three decades, with many experiencing more hot days in a row, a study by nonprofit climate researcher First Street Foundation said.

Southern Maine will be hit hardest by extreme heat. York County’s 90-degree-plus days will almost double to 21 days, and it will see the highest number of 100-degree-plus days — four — of any Maine county. Cumberland County is expected to see its current seven days above 90 degrees more than double to 15 days over the same period.

Increased daytime temperatures and reduced nighttime cooling can trigger exhaustion, stress and even heart attacks, especially among the elderly who don’t adjust well to sudden temperature changes, according to the U.S. Centers for Disease Control and Prevention.

Andrew Russell, 45, eats breakfast near an air conditioner at the Seeds of Hope Center in Biddeford on a hot Thursday Aug. 12, 2021. Russell shares a non-air conditioned, two-bedroom apartment with his wife, their daughter and a roommate. Credit: Troy R. Bennett / BDN

For Maine, which is the oldest state in the nation by median age, extreme heat presents elevated risks. Some 36 percent of heat-related deaths in the United States are people over age 65.

Low-income groups that tend to live in cities with heat-retaining concrete and few green spaces face severe health threats, according to a joint investigation by NPR and the University of Maryland’s Howard Center for Investigative Journalism. Heat also traps pollution.

This is true in larger Maine cities, including Portland, which tend to have “heat islands” of heat-absorbing infrastructure such as pavement, buildings and rooftops. But even smaller municipalities like Biddeford have the problem. Both are trying to mitigate heat build-up by planting more trees and installing more porous infrastructure.

“Everything we have in place was built based on an assumption that our climate was stable,” Hill said. “That assumption is no longer accurate.”

Lori Valigra, investigative reporter for the environment, holds an M.S. in journalism from Boston University. She was a Knight journalism fellow at M.I.T. and has extensive international reporting experience...