October Chill will Quickly be Replaced with Summer Warmth for New England

A large area of Canadian high pressure has built into New England behind a cold frontal passage. This will bring a much cooler air mass to the region for Wednesday and Thursday. Widespread highs in the 50s north and 60s south are likely both days. A rather strong pressure gradient between the high pressure centered just north of New England and the passing Hurricane Humberto well offshore will allow for breezy conditions. Northeast gusts of 20-30mph will be possible, adding to the October chill in the air.

The main weather impact during this otherwise very tranquil pattern will be elevated fire weather potential. High pressure has generally kept this threat lower over the past several days due to light winds. With the increase in winds today and tomorrow, the fire threat will be elevated. Continued sunny skies will help to dry out soils from last week's soaking rainfall and dropping leaves will add ground fuels. The fire weather threat generally increases the farther north in New England you go.

Other than the increased wind gusts from a tight pressure gradient, Hurricane Humberto will also send some large waves toward the New England coastline. A high surf advisory is in effect for all of New England's coast minus Connecticut. Large waves of 6 to 12 feet are likely in the breaking zone. Southern New England will be on the higher end of this zone and northern New England will be on the lower end.

With higher pressure moving directly overhead, the cool days will be accompanied by crisp nights. Rather strong radiational cooling conditions are expected over the next couple nights. Both Thursday morning and Friday morning will be cold ones, with widespread 30s across New England and 20s in northernmost areas. Some chilly nights in September have already led to frosts and freezes across much of northern New England, but some in southern New England will be picking up their first frosts of the season by Friday morning.

The only thing really limiting temperatures from truly bottoming out, especially across southern New England, will be weak warm air advection from a shifting pattern that will bring some summer-like weather back to New England. The rather strong high pressure will slip to New England's south over the weekend, setting up a southwesterly flow and a sharp warm-up. Widespread highs well into the 70s will likely return. There are strong signals already for temperatures to reach 80° across lower elevations of southern and central New England, with the potential for some areas to reach the mid 80s by Sunday.

Below: AIFS showing temperature departure from average on Sunday afternoon:

This early October warmth looks to persist through early next week, with Monday and maybe Tuesday seeing widespread 70s and 80s. There are growing signals for a sharp cold front to push through New England by midweek next week, ending this early fall "heat wave". This cold front will also be New England's next chance at widespread rainfall. It will be mainly sunny and bone-dry until this frontal passage, worsening drought conditions.