Weather

First 90-degree day of the year for many today

Boston hasn’t seen a 90-degree day yet this season. This is only the 7th time a 90-degree reading hasn’t been recorded by this time in the summer. While this is unusual, it isn’t a record—the overall global weather pattern has put the northeastern corner of the country on the cooler side of the average for over a year.

Last summer was not particularly hot, and with meteorological summer just about half over, this summer isn’t looking like a searing hot one either. This doesn’t mean we won’t see any more 90-degree days after today, but it could mean we won’t see any prolonged heat waves.

In this part of the country, a heat wave is defined as three days or more in a row of 90-degree temperatures. We haven’t had a heat wave since the summer of 2013. This isn’t the start of a heat wave and, as a matter of fact, I don’t see any more 90-degree days in store this week.

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Same Pattern
When I take a very wide look at the weather pattern, I notice a continued trend to keep the heat south and west of this part of the country. In many ways, the pattern we are seeing is a continuation of the winter one. During the January through April period, we consistently saw renewed pushes of Canadian air. In the winter, this type of pattern brings us very cold air. In the summer, when it’s warm even in Canada, the pattern brings warm air, but keeps the bigger heat and humidity from reaching us.

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If you are on vacation this week, Tuesday and Wednesday are the least favorable days. As a trough of low pressure approaches from the west, it will pull moisture northward from the Atlantic and increase the opportunity for shower activity. There could also be heavier downpours and thunderstorms during this period.

One forecast shows showers over southwest New England by Tuesday afternoon. These will move northward later in the evening and continue into Wednesday.

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Drought Gone For Now
This pattern of showers at least once a week has wiped any drought from nearly all of New England.

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I’ll have more details here and on Twitter about the timing of the rain showers this week. I wouldn’t cancel plans, but if you can rearrange indoor and outdoor activities, I would suggest keeping outdoor plans away from Tuesday afternoon and Wednesday.

The other notable aspect to the weather this week will be the increase and subsequent decrease in humidity. Tuesday and Wednesday are the most humid days. Wednesday appears to me to be the most uncomfortable, as dew points reach the 70-degree mark or even a bit higher. At these levels most folks, except maybe those who love hot yoga, consider it uncomfortable.

The map below is from one of the many weather models I use. It’s indicating the dew points rise well into the 60s to near 70 by Tuesday afternoon.

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The good news: a push of drier but still warm air returns Thursday and Friday with increasing sunshine. The end of the week will be great for all outdoor activities.
Looking to a period even further ahead, which is subject to big swings, I don’t see any prolonged heat and there may be another push of Canadian air sometime in the 6-10 day upcoming period.

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