Cooling trend this week will peak this weekend before warming again

I went away for the weekend and was able to enjoy some of the amazing weather across New England yesterday. When I got home the landscape had continued its transition from summer to fall and there are now plenty of leaves all over the yard. It’s amazing how all of these leaves will fall to the ground in the next four to five weeks.

End of Growing Season
If you consider the volume of plant material about to die, it’s simply fantastic how much of it is recycled back in the ecosystem. I grind up all my leaves in fall and then put them back into the garden. They make great mulch. The cold weather on the way this weekend is certainly going to accelerate this process and by next week at this time many gardens will be done for the season.


You probably noticed it’s been somewhat muggy this afternoon and relatively warm. I have the windows open because it was colder in the house than it was outside.

A cold front is going to sweep through overnight and push the limited humidity out to sea. Behind this front a cooler, not cold, and drier air mass will prevail for the middle of the workweek. I’ll call this seasonable air, it’s not going to be overly cold or warm for mid-October, just typical.

On Friday another cold front will sweeps by and ushers in the coldest air of the season. This likely means the first major frost and freeze all at once. The first of these is often the hardest to predict in terms of impact. Some plants can actually handle a frost and a freeze for a few hours. It really depends if we have 2 or 3 hours of sub-32 degree weather or 6 to 8 hours of it. I would plan on getting your tender plants and last of the veggies inside before Saturday evening.

The 850 millibar temperature map which helps forecast temperatures clearly shows a pool of cold air destined for the northeast. The colder color in Canada make a bee line for us this weekend before lifting to the north again next week.

gfs airmass 4314.gif

The low temperatures Sunday morning are at or below freezing for much of the area. Notice on the map below from WeatherBell Analytics how cold it is on Sunday morning.
If you have outdoor plans this weekend, such as watching the Head of the Charles Regatta, warmer jackets, hats and even gloves will be necessary.

sunday 19th.png

The final image is called a meteogram. This graph shows temperature and precipitation based on, in this case, the GFS model (American). What I love this chart is showing today is the dip in temperature for the weekend and the rapid recovery next week.

col then warm bostonsf.png

Summer-like post first cold
A period of frost and freeze followed by a warm spell is traditionally called Indian summer. Of course the word Indian has all sorts of potential pitfalls. You could say Native American summer, but I like the term Indigenous summer since, like those who have been part of the this area long before Europeans, so too has this type of weather been a part of New England for centuries. It also roles off the tongue better. Whatever you chose to call it, the cold won’t last very long.



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