Everett Nichols of Everett Nichols Roofing carries plywood up a ladder Monday while working on the roof of an apartment house in Waterville. Nichols, who has been roofing for 40 years, says hot weather does not prevent him from working. He says if it is 95 degrees on the ground, it can be about 115 degrees on a roof. Rich Abrahamson/Morning Sentinel

AUGUSTA — This week is going to be a scorcher. This summer might be hotter, too.

Temperatures are forecasted to reach the upper 80s and mid-90s throughout nearly all of Maine, potentially setting records as a “heat dome” washes hot and humid air over New England, according to the National Weather Service. Experts say high temperatures this week are just the start of what is expected to be a warmer-than-average summer.

Hot weather and high humidity will pose health risks to tens of thousands across the state, experts say, and heightened electricity use from air conditioners and heat pumps may place stress on Maine’s electrical grid.

Elderly people, children, people with pre-existing conditions and pets are most at risk from extreme heat. The main symptoms of heat exposure are muscle cramps, shortness of breath, excessive sweating and dizziness, according to Maine Emergency Management Director Vanessa Corson.

Deaths from heat exposure have risen steadily across the country in recent years, according to the U.S. Department of Health and Human Services. The department projects that extreme heat and subsequent deaths “will become more frequent and intense in coming decades.”

Staying inside and out of the sun, drinking lots of water and refraining from outdoor activity during the hottest parts of the day are among the best ways to stay safe and cool during periods of extreme heat, Corson said.

“Stay out of the sun as much as possible. If you can, shift your outdoor activities to early morning or later in the evening,” she said. “Stay inside someplace cool during that peak time of the day.”

Several communities throughout the state are opening cooling centers this week. The Augusta Civic Center, 76 Community Drive, will have a cooling center open from 8 a.m. to 5 p.m. Tuesday through Thursday. In Oxford County, Otisfield will host a cooling center from 8 a.m. to 8 p.m. Tuesday through Thursday at the Otisfield Community Hall, 292 Oxford Road.

A statewide list of cooling centers is available at Maine Emergency Management Agency’s website or by calling 211.

The heat wave will be buoyed by high temperatures persisting through the night, according to NWS meteorologist Jerry Combs. Low overnight temperatures are forecasted to sit around 70 degrees, he said.

“It’s going to be very hot, very humid, and to make things worse, it’s going to stay very warm at night, too,” Combs said.

Temperatures in Portland may set records, Combs said, rising from the mid-80s on Tuesday to the upper 90s later in the week. The high temperature will be 94 degrees on Wednesday and 96 on Thursday, according to NWS forecasts.

Portland’s record high temperature on June 18 is 91 degrees, recorded in 2018. June 19’s record is 94 degrees, recorded in 1995. On June 20, the record was set in 2020 at 93 degrees. For the first time since Portland’s weather records began in 1940, the city’s daily low temperature set an all-time heat record last year when it was 60 degrees or more for 32 consecutive days.

The heat also will reach record levels in Augusta and much of central Maine. High temperatures will remain in the mid-90s Tuesday through Thursday, peaking at 97 degrees on Thursday.

For June 18 the heat record in Augusta was set in 1994 when the temperature hit 93 degrees. The record for June 19 was set the following year at 98 degrees.

In Lewiston, temperatures are expected to sit in the 90s through much of the week. Tuesday’s high temperature is 91 degrees, which will rise to 96 on Wednesday and 97 on Thursday. Combs said Lewiston weather records do not go back far enough to draw meaningful historic comparisons.

Across Maine, heat indexes will sit in the mid-90s on Tuesday with the potential to reach upwards of 105 on Wednesday and Thursday as hot and humid air accumulates statewide, Combs said. The heat index factors together heat and humidity to measure how hot weather feels to the human body, similar to how wind chill measures cold weather.

“The apex of it looks like Thursday, it cools off across most of the state on Friday,” Combs said. “We’re probably going to have some more clouds and maybe some showers by Friday, so that should limit temperatures a little bit.”

Zach Nickerson, left, of Fairfield and Jon Roy of Albion spin their personal watercrafts June 9 at China Lake in China. Temperatures this week are expected to send people across the region to the water to cool off. Rich Abrahamson/Morning Sentinel

This year’s heat wave comes earlier than Maine’s last, which arrived in July 2022 when the state saw temperatures near 100 degrees and unhealthy ozone levels for nearly the entire month.

With more people staying inside and turning up their air conditioners and heat pumps, Maine’s power grid operators say they will be able to handle a surge in electricity usage this year, according to ISO New England communications specialist Mary Cate Colapietro.

ISO New England is the company that manages electricity for most of New England, supplying power to localized delivery companies like Central Maine Power and Versant.

“While demand may reach peak levels so far for the year, these levels are within our expected range for the summer season,” Colapietro said in an email. “We are not anticipating any issues due to the anticipated hot weather.”

This week’s heat wave is fueled in large part by what meteorologists are describing as a “heat dome,” in which hot, humid ocean air is trapped over an area by high atmospheric pressure. Heat domes and heat waves often occur simultaneously.

“Essentially, there’s a ridge of high pressure setting up along the eastern continental United States, pushing a lot of hot air up with it,” Combs said. “There’s not going to be a lot of wind to cool things off, and there’s not going to be a lot of cloud cover to help out either.”

This summer is forecasted to be about 50% hotter than average for both Maine and most of the U.S., according to the National Oceanic and Atmospheric Administration’s Climate Prediction Center.

Graphic courtesy of National Oceanic and Atmospheric Administration Climate Prediction Center

The heat is caused by several factors, officials say, ranging from climate change to La Niña, a global weather pattern that is predicted to ramp up this summer.

La Niña is a climate pattern characterized by cooler-than-average sea surface temperatures in the central and eastern equatorial Pacific Ocean that has implications for weather across the globe. In New England, La Niña generally causes warmer summers with lower precipitation, Combs said, which could exacerbate what may be an already warmer-than-average summer.

“It’s still too early to say what exactly this summer will look like, but it’s definitely shaping up to be hot,” Combs said.