DAYS 1-5 (AUGUST 16-20)
This set-up mimics spring in some ways, with a frontal boundary stuck just to our south, and us on the cool side. Of course, it being August, it’s a “warm” cool and the humidity is more noticeable as a result. But once again, it’s not a combo of heat and humidity, which has been lacking this summer. Through August 15, Boston’s Logan Airport has recorded only 4 days of 90 degrees or higher, with the highest of the summer 91 so far. Inland, it’s a slightly different story, where there have been a few more 90+ days, but still not that many, and some of the seasonal highs are in the middle 90s, but these bouts have been sparse and brief. And there are no 90 degree days in sight right now either, at least through this 5-day period to start with. Today we remain locked on the cool side of the boundary with lots of clouds and a light onshore breeze. A disturbance passing by will trigger some showers mostly south of I-90 this morning, maybe an embedded thunderstorm close to Cape Cod. Slight drying this afternoon allows for breaks of sun, and maybe just enough solar heating to trigger a pop up shower over the hilly terrain of southwestern NH and/or central MA, but for the most part, most of the region will see a rain-free day with below normal temperatures and not much wind. Tonight, the clouds want to break, but enough low level moisture exists for an increase in stratus clouds and areas of fog to develop, so it could be variable enough that you could be driving along and see stars through the clouds and 1 mile later be enshrouded by a fog bank. An increasing southerly air flow on Thursday will help break up any fog and the lowest clouds, but there will still be a fair amount of clouds due to the high humidity at lower levels. At the same time, other clouds from an approaching trough will be moving in from the south and west, so any sun we do see on Thursday will be rather limited. An initial disturbance may incite a swath of showers in the South Coast / Cape Cod region during the afternoon before a ribbon of scattered to numerous showers and thunderstorms moves into the region from west to east overnight into Friday. This will occur as the front that has been sitting to our south finally lifts through as a warm front. If there is a break with more sun between that area and one more with an approaching cold front Friday, one more broken to possibly solid line of showers and storms on Friday late morning to early afternoon can be more potent. I still think the frontal timing and speed is fast enough that we see a drying trend from west to east during the later hours of Friday, and most especially Friday evening and night. After this mess of clouds, humidity, and showers exits, we set up for a weekend of fair weather and low humidity. Saturday will be the breezier of the 2 days with a fresh west to northwest breeze and passing fair weather clouds, while Sunday likely features lighter wind and more sun.
TODAY: Clouds dominate. Sun breaks rare but possible. Shower chance is highest south of I-90 with a possible t-storm for Cape Cod until late morning. Isolated showers southwestern NH / central MA later on. Patchy drizzle possible. Highs 75-82. Dew point in 60s. Wind E up to 10 MPH, shifting to SE later.
TONIGHT: Lots of clouds. Areas of fog. Lows 61-68. Dew point 60+. Wind SE to variable under 10 MPH.
THURSDAY: Lots of clouds / limited sun. Shower chance highest in the afternoon over southern RI and southeastern MA. Late-day showers may reach eastern CT and central MA to southwestern NH. Highs 76-83. Dew point rising toward 70. Wind SE to S increasing to 5-15 MPH, higher gusts especially near the South Coast.
THURSDAY NIGHT: Mostly cloudy. Showers likely. Chance of thunderstorms. Areas of fog. Lows 65-72. Dew point middle to upper 60s. Wind S 5-15 MPH.
FRIDAY: Variably cloudy. Scattered showers and thunderstorms , diminishing from west to east midday through afternoon. Highs 78-85. Dew point 60+. Wind S shifting to W 5-15 MPH.
FRIDAY NIGHT: Partly cloudy. Lows 60-67. Dew point falling below 60. Wind W 5-15 MPH.
SATURDAY: Sun/cloud mix. Highs 78-85. Dew point falling below 50. Wind W 5-15 MPH.
SATURDAY NIGHT: Clearing. Lows 55-62. Dew point 40s. Wind W 5-15 MPH, diminishing.
SUNDAY: Mostly sunny. Highs 78-85. Dew point near 50. Wind W up to 10 MPH.
DAYS 6-10 (AUGUST 21-25)
General pattern should feature a northwesterly upper level air flow with a ridge of high pressure in the central US and a trough of low pressure from eastern Canada to northern New England. This pattern keeps major heat out, but leaves the door open for passing disturbances and shower/storm chances, but not an overly wet set-up.
DAYS 11-15 (AUGUST 26-30)
No big changes to the 6-10 day pattern expected during this period either. Temperatures near normal but somewhat variable. Brief shower chances.