It's officially the month of Halloween, pumpkins, fairs and fall foliage. Average high temperatures drop a good 15 degrees from October 1st to October 31st. The month will be starting off warm and rather un-October like, how long will that last? Find out below.
TEMPERATURES
The first week of October will feature a classic ridge-in-the-east-trough-in-the-west pattern. This will allow very warm conditions in the middle of the county to spill eastward, into New England. This will lead to above temperatures for most of the week, with widespread 80s likely on Monday (average highs are in the 60s for most in early October). This warm weather will persist for much of the week, although Tuesday (October 3) looks to be the warmest day as a cold front cools things off a bit for eastern New England by Wednesday.
By the end of the week (October 6-7), the weather pattern will be changing. The trough in the western part of the county will shift toward the east by this time. This will cool the region off significantly. By week two of the month (October 8-14), New England will be looking at below average temperatures.
This is supported by a negative NAO and positive PNA. As discussed in previous monthly outlooks, a negative NAO favors cooler, more unsettled weather in the east while a positive NAO favors warmer and more stable weather. The PNA works the same for the west coast. By the second week of the month, these two factors will allow for a polar air mass to push into New England early next week. This possibility has been picked up by all major models.
Just how chilly it gets remains to be seen next week. It needs to be noted that this is a polar air mass, not an arctic air mass. Polar air masses originate from higher latitudes (i.e. Canada), but still south of the arctic, so they are not as cold as arctic masses that push into New England in the heart of winter. This is to say we're not expecting a "taste of winter" next week, just cooler than average temperatures. These temperatures will feel particularly cool after the warm start to the month.
Heading into the second half of the month, there are some signals pointing to another potential warm up (warm up being relative to average). However, as we get deeper into October, cold fronts become stronger and troughs in the jet stream dig deeper. The second half of the month could play out like the first half, with warmer times and cooler times going back and forth.
Overall, we're predicting a very up and down and up again month temperature-wise, which is expected in New England in October as the summer set up and incoming winter setup begin to clash. The entire month may end up averaging above average, but this will likely mainly be due to the warmth coming up this week.
RAIN/SNOW
The first week of the month will be dry and sunny under high pressure. Heading into this upcoming weekend, a cold front will cross the region, ushering in the cooler air mass discussed above. This will lead to unsettled weather returning once again. The dip in the jet stream would favor cloudy, more unsettled weather continuing. This can be seen in the Climate Prediction Center's 6-10 day precipitation outlook, which currently covers October 6-10.
There are signals pointing toward drying out after this period, with a return to seasonably average precipitation. As far as snow, current signals do not favor early season flakes, however, if a cold air intrusion and a storm system can be timed right, it can always happen. As recently as 2020, a storm dumped 3-6 inches of snow across New England. There was also the infamous Halloween Weekend Storm in 2011 that dropped upwards of 30 inches in New England.
FALL FOLIAGE
The start of fall foliage has been a bit delayed in New England this year. Typically, Vermont's Northeast Kingdom and New Hampshire's Great North Woods near peak by late September. This year, these areas are looking to peak by this upcoming weekend.
The entirety of New England can expect peak foliage to occur a bit later than usual this month. The cooler weather coming after this week should help get things moving more. Colors are expected to be vibrant this year thanks to all the rain this summer.
LOOKING BACK
Our September outlook panned out just about as expected. We predicted a warmer than average start to the month with a cooler than average end. From September 1-15, Boston saw 8 days above average. From 16-30, Boston saw 9 days below average.
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