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Dave Epstein

July will be the warmest month ever recorded in Boston

Lane Turner/Globe Staff/File/2018/Globe Staff

The temperature at Logan International Airport was 93 by 1 p.m. Wednesday, making it the 12th day of the year that temperatures have reached 90 or higher, all of them this month.

Basically, we have just experienced a year’s worth of 90-degree weather in 31 days.

If you live in the state’s interior, it’s been even hotter. Norwood has seen a whopping 20 90-degree days this year, 19 of them this month.

All of this heat is adding up to the warmest month in Boston since records began being kept in 1872, not to mention the warmest July.

There are areas of the United States where it has not been as warm and it has actually been cooler than average.


We can’t say that this month’s temperatures can specifically be blamed on climate change, but the trend is clear, we are getting warmer — and quickly — by weather and climate standards.

Southern New England has been one of the warmest regions of the United States this month, when compared with the average.WeatherBell

If you went back 100 years, the average number of days Boston would reach 90 degrees was around eight. That number has increased by 50 percent and now stands around 12.

When you look at 30-year averages, the month we’ve just experienced is similar to what a typical summer would be like around Norfolk, Virginia, not Southern New England.

When you compare July 2019 to 30 year averages the past month has been more similar to Norfolk, Virginia. NOAA Data

It’s not just the Boston area that’s been warm. Portland, Maine, will record its warmest July ever, as well as parts of central Connecticut around Hartford.

Portland, Maine, has experienced a very hot July. <a href="http://twitter.com/RyanBretonWX">@RyanBretonWX</a>

There’s no single reason why it’s been so warm or why this season, which many of you look forward to, has become so extreme. The Gulf of Maine is the fastest warming body of water on the planet and it’s definitely contributing to the heat. The warm ocean can keep the air adjacent to it at an above-average temperature, especially at night, in places like Boston and Portland.


The Gulf of Maine is the fastest warming body of water in the world! NOAA

The overall weather pattern itself has brought a lot of high pressure and multiple days with southwesterly winds. This flow tends to propel warm and humid air masses into New England. The pattern is actually typical, but the end result of extended warmth isn’t.

Strong high pressure over the Southeast US has kept it very hot in southern New England this month.Tropical Tidbits

All this weather is occurring with a warming climate in the background, which adds additional pressure for recordbreaking heat. Ask folks in the mid-Atlantic around Virginia, Maryland, and parts of New Jersey what they think of summer. I suspect you’ll find a lot of folks who would tell you it’s just too hot to do very much outside, especially at midday.

Southern New England is on a trend that will bring more and more years where our summers will resemble those in the mid-Atlantic.

If projections are correct, in the next century most summers in greater Boston will be more like you would experience today around Philadelphia, Pennsylvania, or Norfolk, Virginia, rather than what earlier generations knew.

The average temperature for meteorological summer June-August is clearly on the rise. NOAA

Follow Dave Epstein on Twitter @growingwisdom.