David Epstein: How long will this oppressive heat last?

 —Dave Epstein for The Boston Globe

The heat is on, and it looks like it’s going to continue for much of this week and perhaps even longer.

We are on pace to have the warmest first week of August ever in Boston. The current average this month is 80.6 degrees, and that’s just below the all-time warmest start to August. We have two very hot days coming up, so the record is in jeopardy.

Mean average temperature August 1 to August 7 for the Boston area

Average temperature during the first week of August since 1872. —David Epstein / NOAA data

If you think back to our cool and wet April, many of you were already worried about a cool summer. Obviously, that has not materialized. It’s a good point to remember that what happens in April and May does not translate into what’s going to happen in June, July, and August. July was a hot month, and August is picking up right where it left off. While I realize extremes are actually the normal here in New England, we are at the upper end of the scale for both temperature and humidity this month.


Our collective memories tend to be short, and it’s worth pointing out that August 2016 is in the books as the hottest August in Boston since records started back in 1872. As the planet continues to warm, we can expect more of these records to happen.

We still have a lot of this month to go, but it is certainly possible that we’re going to get very close to or even break that record from two years ago. Take a look at the August we experienced in 2016 and you’ll notice that there were several days in the 70s. There were also a few days in the lower 80s, neither of which we’ve seen so far. In order to become the warmest August on record we’re going to have to see very few days in the 70s.

Mathematically, the more we front load this month with abnormally warm conditions, the harder it’s going to be for the month to be anything but warmer-than-average. We would have to dramatically cool off during the second half of the month for this August to not end up warm.

The reason for the heat is an area of high pressure that is out in the central Atlantic called the “Bermuda High.” There’s nothing unique about this particular area of high pressure except its position, which is why we call it a Bermuda High. The high is ever present in the summer, but its strength and exact position varies week-to-week, month-to-month, and year-to-year. Since July, this high has continually re-established itself in a way that has provided very warm conditions to New England. We’ve had more of a southerly flow rather than a westerly flow, which has kept the humidity unusually high but also prevented us from breaking many high temperature records.


Monday and Tuesday will be the hottest days this week. It will feel near 100 degrees each afternoon, and a heat advisory is posted for most of the area, except Cape Cod.

Somewhat drier air, but still warm-to-hot, is headed to us this weekend. There are conflicting signs of what will happen a week from now, with a possibility of rain or a continuation of the heat for even longer.

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