Oliver Taylor, 6, of Saco soaks in the last moments of his time at the beach last June during Maine’s record hot summer. Shawn Patrick Ouellette/Portland Press Herald

Last year was Maine’s hottest on record, with midsummer and late fall heatwaves and record temperatures in the north driving the average annual statewide temperature 5 degrees above the historical average, records show.

It was Earth’s hottest year on record, too, and the first time in recorded history that the annual average exceeded the climate threshold established in the 2015 world climate treaty.

The United States and 17 of its states, including New Hampshire and Vermont, also logged their hottest years on record.

Heat wasn’t the only sign of the changing climate in Maine. Across the state, 2024 was a year of weather extremes.

Most people will remember 2024 for its back-to-back January storms that caused $90 million in flood damage. But it was also a year of record early ice melting on Maine lakes, bath-warm lakes in July and shattered heat records in Caribou, Presque Isle and Millinocket.

And while the year began with extreme precipitation events and floods, it ended with the driest fall on record in Maine, causing a drought that continues in 2025.

Like much of the eastern U.S., winter is Maine’s fastest warming season, records show. Central Maine’s climate is slowly turning into that of a Connecticut, with a warmer, shorter and less snowy winter.

The three-month period from Dec. 1, 2023 to Feb. 29, 2024 continued that trend with an average of 24.4 degrees, matching the record set in 2016 as Maine’s warmest winter.

A wave breaks against a sea wall in front of homes along Wells Beach during a January 2024 storm that battered the coast and flooded inland communities. Gregory Rec/Staff Photographer

However, the summer of 2024 also was Maine’s hottest summer on record, with an average daily temperature of 66.4 degrees.

“We had a warmer than usual spring, a record hot June marked by a heatwave and very high overnight temperatures, and a record hot fall,” said state climatologist Sean Birkel, a research assistant professor at University of Maine. “Our last four years rank among our warmest.”

Overall, Maine’s average annual temperature was 45.1 degrees, national weather records show. It was 0.8 degrees warmer than 2023, Maine’s third hottest year on record. Maine’s second hottest year was 2010, which at 44.6 degrees was 4.5 degrees above average.

The heat waves that turned 2024 into a record breaker are more common and intense because of global climate change. Scientists agree the climate is warming because of the burning of oil, gas and coal that release heat-trapping greenhouse gases into the atmosphere and warm the Earth.

Hotter summers will have public health impacts, state health officials say: underlying medical conditions like heart failure, COPD, diabetes and asthma will get worse, and heat-related emergency visits will increase. The health impacts will be felt even more in communities where residents are more vulnerable, such as more older adults living alone or more people living in older housing with no air conditioning or in neighborhoods with few trees and a lot of pavement.

Globally, the United Nations says sustained temperatures of more than 2.7 degrees above pre-industrial times would threaten Amazon rain forests and coral reefs, cause melting of arctic ice sheets and contribute to billions of deaths from disease and famine. The past year was the first time the Earth exceeded the threshold, but year-to-year variations are not expected to trigger such catastrophic effects.

RESPONDING TO THE HEAT

A growing number of local communities are taking steps to respond to the harmful consequences of Maine’s rising temperatures, according to Parker Gassett, a marine and coastal communities specialist at UMaine’s Maine Climate Science Information Exchange.

Nine Blue Hill-area towns are developing a plan to reduce the regional risk of climate-driven wildfire, Gassett said. Ellsworth has just kicked off a three-year plan to “re-tree” its city to improve air quality, increase shade and reduce flood risks, all side effects of climate change.

In Camden, an 85-year-old gardener and environmental activist, Beedy Parker, is promoting the campaign to plant 50 shade trees a year to “keep Camden cool” in the face of Maine’s warming climate to replace the old street-side trees that are coming down.

“We’ve had some hot days on the coast this summer,” Parker wrote in the Midcoast Villager in August. “Walking down a shaded street can be a pleasure, especially when each shade tree is big enough to even create a little breeze. But trudging through to blazing bare spots is hard.”

Timothy Mcninch, of Biddeford, sips ice water while on a break from working on an outdoor construction site in June. Shawn Patrick Ouellette/Portland Press Herald

The June heatwave was compounded by high humidity, which led to newborn losses and productivity declines for some livestock farmers, said Rachel White, an assistant professor and livestock educator at UMaine Cooperative Extension.

“Deaths that are directly related to heatstroke are still very few and far between,” White said. “But we are seeing more indirect losses and challenges in sustaining health and productivity for animals that are already stressed, like the very young, the very old or those being weaned.”

Like any other kind of stress, heat can lead to a compromised immune system, which allows the parasites and pathogens that flourish in hot, humid conditions to “really take advantage of the moment,” said White, who specializes in sheep, goats and chickens.

White works with farmers to find ways to help their livestock endure the heat. It starts with keeping the animals in good health, but can include installing fans or misters in coops or barns, planting shade trees in pastures or extending a fenceline into a stand of trees. It might also mean embracing a heat-hardy breed.

FROM FLOODS TO DROUGHT

After the wet start last January, Maine’s average statewide precipitation total for the year — 43 inches — was close the historical average, ranking 60th out of 130.

But that masks a record-breaking fall drought. The climatological fall, which runs from September through November, was the driest on record, Birkel said.

According to the U.S. Drought Monitor, 61% of Maine was in a moderate drought as of December. More than 92% of the population lives in a drought-stricken region. While agriculture has largely been spared because of the drought’s late onset, it has caused a spike in dry well complaints.

Below average snowfalls are contributing to the drought. As of last week, the amount of statewide snow that has fallen this winter was the lowest in the last several years, Birkel said.

“If we don’t see more snow, we could see a continuing precipitation deficit going into the spring that will have potential hydrological impacts,” Birkel said. “Basically, that means the drought we saw last fall would no longer be a short-term weather event, but would continue into the spring.”

People cool off in the wading pool at Deering Oaks Park in Portland during a stretch of heat and humidity last summer. Gregory Rec/Portland Press Herald

Rising temperatures, a declining snowpack and even greater frequency of extreme weather doesn’t necessarily mean that Maine will face annual droughts, Birkel said. But as Maine warms, it is likely to experience more drought, as well as more heavy rainfall events, in any given year.

Despite the drought and the heat, most of the vegetable and fruit farmers that David Handley works with at the Cooperative Extension felt grateful for the weather, which was much better than the heavy rains of the year before that made it hard for many growers to plant or harvest their crops.

Strawberry farmers struggled because the warm weather ripened the berries earlier than usual — most families don’t come out to pick until after school ends — and resulted in a shorter season, both because the fruit ripened faster and because an invasive pest attacked the berries earlier than usual.

Vegetable crops flourished, especially those that like the heat, such as tomatoes, peppers, corn, squash and pumpkins. Even crops that prefer the cool like peas, carrots and broccoli did OK because farmers used water supply from the previous year to irrigate the fields, despite the drought.

“Heat and dryness keeps many plant diseases from infecting crop fields,” Handley said. “Hot and sunny conditions also encouraged people to be outside, so pick-your-own fields, farm stands and farmers markets were all busy with good crowds most of the season.”