Stein:
The average date of the first 90-degree reading in Boston is June 8th, and we have not hit one officially so far at Logan Airport. It’s not impossible that this weekend brings the first 90-degree day, but because Logan sits — basically — in the water, it could reach 90 degrees in downtown Boston and still only be 80 to 85 at Logan Airport.
The heat will be neither noteworthy nor long-lasting this weekend, but many inland areas will reach 90 degrees. You can see that on Saturday, when the high temperature predicted by the GFS is near 90 degrees. Coastal areas should remain cooler.