DAYS 1-5 (SEPTEMBER 21-25)
High pressure hangs on through Friday with fair and pleasant September weather for the last 2 days of summer, but while this is going on, east-facing and south-facing shores will have high rip current risks due to distant Hurricane Nigel’s long-period swell, so keep that in mind if you have plans to be at the coast and in the water. Meanwhile, subtropical low pressure will develop and organize off the US Southeast Coast and drift north to northwest toward the coastline late this week. Its northern rain shield will make a run at southern New England, but I’m still of the meteorological opinion that guidance is over-forecasting the scope and aggressiveness of this rain shield, and while I’ve introduced a lot of cloudiness to the forecast for both weekend days, I don’t think the rain is going to blast into the region and wash out Saturday. I think some of it gets to the South Coast especially Cape Cod, but much of it runs into dry air in place and gets obliterated, and then peels off to the east, waiting for a weaker version of low pressure, which has interacted with the coastline now for many hours, to come drifting northward to bring some wet weather to the region on Sunday. After that, it will get shoved southeastward Monday by high pressure in Canada, though an upper level disturbance swinging through will result in lingering clouds and the chance of some lingering showers that day, if all goes as I expect it to. Reminder: Fall arrives with the autumnal equinox at 2:50 a.m. Saturday.
TODAY: Sunny. Highs 68-75, coolest coast. Wind NE up to 10 MPH.
TONIGHT: Mostly clear. Ground fog patches low elevations. Lows 47-54. Wind variable under 10 MPH.
FRIDAY: Mostly sunny. Highs 67-74, coolest coast. Wind variable up to 10 MPH with coastal sea breezes.
FRIDAY NIGHT: High clouds increase. Ground fog patches low elevations. Lows 48-55. Wind calm.
SATURDAY: High overcast, except thicker/lower overcast may bring some rain to South Coast / Cape Cod region. Highs 66-73. Wind E 5-15 MPH.
SATURDAY NIGHT: Mostly cloudy. Patchy fog. Lows 53-60. Wind E up to 10 MPH.
SUNDAY: Cloudy. Chance of rain, favoring the South Coast but possible anywhere. Highs 62-69. Wind E 5-15 MPH.
SUNDAY NIGHT: Mostly cloudy. Lingering showers and/or drizzle. Patchy fog. Lows 55-62. Wind E to N up to 10 MPH.
MONDAY: Lots of clouds. A possible shower. Highs 65-72. Wind N 5-15 MPH.
DAYS 6-10 (SEPTEMBER 26-30)
High pressure builds in from Canada with a stretch of generally fair weather during the middle of next week with near to below normal temperatures, then a moderating trend when a disturbance may swing into the region with some unsettled weather toward the end of the period, but less confident of that.
DAYS 11-15 (OCTOBER 1-5)
October’s early days show hints of weak westerly flow over our region, but a Rex block type set-up with high pressure dominating eastern Canada while low pressure hangs out to our south. This leaves the region vulnerable to battle zone unsettled weather, but for now my initial leaning is that high pressure to the north will be close enough / strong enough to keep us mainly fair. Long way to go to sort out the early October weather…