It could be a hot one, Massachusetts. But that isn’t shocking to climate researchers.
Weather officials project that the next three months will be warmer, and possibly wetter, in Southern New England than may normally be expected for this time of year. For those who keep a close eye on climate and weather trends, that forecast is in line with decades of warnings.
“What we consider normal weather — temperature and precipitation — has changed, said Michael Rawlins, a climate expert at the University of Massachusetts Amherst. “It’s warmer and wetter here than what folks generations ago would have considered normal.”
A three-month forecast released by the National Weather Service indicated that much of the United States could be due for a warmer summer than those of recent decades. But for New England and parts of the Rocky Mountain region, there is a greater chance of an even toastier next three months.
The weather agency’s Climate Prediction Center also foresees above-average rainfall in the coming months in Massachusetts, Rhode Island, Connecticut and parts of southern New Hampshire and Vermont.
The forecast did not surprise Rawlins, the associate director of the UMass Climate System Research Center.
“Summer temperatures in Massachusetts have been above average every year since 2005,” he said. The summers of 2020 and 2021 were among the warmest on record since 1895.
Not every summer has been warmer than the previous one. But since the turn of the century, only two summers — 2000 and 2004 — were cooler than the average 20th-century summer, according to Rawlins.
The cause, he said, is that gases produced by humans have accumulated in the atmosphere, trapping increased amounts of the sun’s heat. As a result, the definition of what a typical summer might be has changed.
“Our normal climate has warmed,” Rawlins said. “We are in a new normal as a result of increasing greenhouse gases.”
When climatologists think about a “normal” summer, they are talking about the average temperatures over the most recently completed three-decade period. Thus, the current normal period for examining climate covers the 1990s, 2000s and 2010s.
That 30-year period was hotter than the previous “climate normal,” which extended from 1981 to 2010.
“Each successive 30-year normal period is warmer because our climate is warming,” Rawlins said. “It’s inconceivable that a 30-year normal period will be cooler than the previous one over coming decades. We can expect the normal to keep getting warmer.”
The summers are also getting wetter. The summer of 2021 was Boston’s warmest and third-wettest on record. While in a normal year — between 1991 and 2020 — the city’s average rainfall would have been about 10 inches from June through August, it was nearly 20 inches during the summer of 2021.
That’s also not surprising to climate scientists. More days each year are seeing heavy rains, and the effects have been greater in the Northeast than any other part of the country, Rawlins said.
“The amount of days in a year with more than an inch of rain has gone up,” he said. “We’re now seeing several more days each year with one inch or more of rain.”
“We’re a wet climate here,” Rawlins continued. “And it’s getting warmer and it’s getting wetter.”