Weather

One of the warmer periods of summer brings us into September

Meteorological summer comes to a close today as the warmest quarter of the year is just about over. While statistically this is the case, the fringes of any season often resemble the previous or the next one. Early September often feels like summer as late November can often feel like winter.

Depending on the source, meteorological summer is thought to end September 4th. According to the National Weather Service in Caribou, “September 5th is meteorologically the first day of fall. It begins the three-month period when temperatures fall most rapidly and the one month period when day length decreases most rapidly.” No matter which date you use, this year the first week of September is going to resemble mid-July. With the exception of the lower sun angle and about two hours less light than mid-June, the next 7 to 10 days will feature conditions which are quite remarkable for September.

The record highs for this period are all well into the 90s or even the century mark as is the case on September 2nd and 7th. I don’t see this period of summer heat as being record breaking, although there will likely be some complaints from the kids sitting in hot classrooms.

The reason so much heat is building now is a strong area of high pressure is anchored off the southeast coast. This high pressure, typically, is beginning to weaken in September. Known as the Bermuda high, it will pump warm and humid air northward across much of the eastern half of the country.

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Places like Chicago, Detroit, Washington, D.C., New York, and much of New England will have some of their hottest stretches of the year.

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The map below shows high temperatures for Tuesday. There will be sea breezes along the coast, but inland areas will turn very warm to hot in the afternoon. There is a large area of 90s visible tomorrow across many states from the Midwest to the East Coast. The pattern will continue for about a week.

tues sept 1 102521.png

During this week’s heat the humidity will be present but not oppressive. There may be a day or two when the dew points even fall into the upper 50s, but I don’t expect a prolonged period when they will reach into the 70s as we had about a week ago.

After a relatively seasonable summer temperature wise, it’s not unprecedented or even unusual to find warmer than average weather in September. August 1957 was a cool month, averaging nearly 3 degrees cooler than the long-term averages at the time. A month later, September of that year averaged over 2 degrees above the 30-year normal. The August pattern completely flipped the following month.

This was all well predicted by most of the long-range models, and if you have been reading the blog the past several weeks, you know I’ve been relaying this information to you.

It does look like some cooler weather will return to the area in about a week. Along with this cooler weather, some very dry air is also likely to arrive. When it does become very dry again, that’s when you will say the feel of fall is in the air, but until that time, it’s summer breezes.

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