Boston Mayor Marty Walsh has declared a heat emergency and ordered cooling centers opened across the city ahead of the dangerously high temperatures expected to affect the region this weekend.
The heat emergency starts at noon Friday and runs through Sunday night, coinciding with an excessive heat warning issued by the National Weather Service. Cooling centers will be open at Boston Centers for Youth & Families community centers, and residents will be allowed to swim at city pools free of charge.
Numerous other communities across New England have also taken similar steps ahead of the expected heat wave.
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Braintree will open the Braintree Department of Elder Affairs at 71 Cleveland Avenue from 8:30 a.m. - 4:30 p.m. Friday and Saturday.
Before the heat moves in, downpours and scattered showers continue in the forecast Thursday night, mainly south along the more humid airmass boundary. The rain tapers off overnight, and we will have Friday morning clouds south with increasing sunshine in the afternoon. By late afternoon, our temperatures will be in the low 90s inland, with heat index temperatures in the mid-90s.
We are watching the possibility of a storm complex developing Friday afternoon in New York and Pennsylvania. As that complex travels around the ridge of high pressure (dome of heat) - we call these “ridge runners” - they can grow in size and strength to a derecho event.
There is a small chance that the northern edge of these storms may move into western New England sometime Friday evening. Stay tuned for further updates on that.
The heat index is how uncomfortable we feel based on the effects of the temperature and humidity. We sweat to cool off and normally the sweat evaporates quick enough to cool us off.
When we have high humidity levels, our bodies can’t cool as efficiently or as quickly as in dry air. The chance of overheating, or heat stroke, will be high this weekend as temperatures won’t even cool off overnight. So the stress on our bodies will build through Sunday.
Saturday afternoon will bring the hottest temperatures of the season to the northeast. Highs will be around 100 degrees and heat index values 100-110. This is dangerous heat, and we will not get much relief overnight as lows will be around 80 and still humid.
Speaking of 100, the last time we hit 100 in Boston was on July 22, 2011, and it was 102. Hartford hit 100 on July 18, 2012; Providence hit 101 on July 22, 2011; Worcester hit 102 on July 4, 1911.
The record high for Saturday in Boston is 99 which was set in 1991. Worcester’s record is 95 also set in 1991. We forecast to at least tie both records.
Sunday will be just as hot in the 90s with heat index temperatures also in the 100 to 110 degree range. A cold front approaches the area and will bring scattered storms to northern and western New England by afternoon.
That cold front will bring us relief from the heat, but will keep storm chances across the northeast for the start to next week. Highs cool off to around 80 by mid-week.