DAYS 1-5 (JUNE 30 – JULY 4)
High pressure slides offshore today as we wrap up June with a fair, warm day. A south to southwest air flow will keep coastal points, especially south-facing ones, cooler. Some stratus and fog will flirt with the islands this morning, and a batch of high and mid level clouds will drift up from the southwest later today, otherwise look for plenty of sunshine overall. Overnight / early Tuesday, a batch of clouds moves in and a round of showers (possibly a thunderstorm) will move through the few hours either side of dawn Tuesday, a result of the arrival of moisture and instability. Tuesday’s weather will be quite humid and very warm and we should break out into a sun/cloud mix after the initial batch of wet weather. With the approach of a cold front we’ll need to watch for showers and thunderstorm chances to increase in the afternoon into the evening. There are still some details to work out with this – scattered individual cells vs. a line or line segments. I think we will see a bit of both, and some storms do have the potential to be strong to severe, so prepare to be weather-aware. High pressure builds in behind the cold front with fair, warm, but lower humidity weather Wednesday. Thursday will be somewhat similar, but the approach of a disturbance from the northwest can trigger a few afternoon to early evening showers and thunderstorms of the isolated to scattered variety, so if you have outdoor plans that day, be aware of that possibility. Yesterday I was a bit nervous that this system would be sluggish, but it does look like it will exit the region in time for a fabulous fourth – very nice weather with sun, fair weather clouds, mild to warm air and low humidity for Friday.
TODAY: Some low clouds / fog Nantucket & Martha’s Vineyard early, otherwise sunshine dominates but some clouds arrive later in the day. Highs 76-83 South Coast / Cape Cod, 83-90 elsewhere. Dew point in 60s. Wind S 5-15 MPH.
TONIGHT: Increasing clouds. Patchy fog. Showers possible toward dawn. Lows 65-72. Dew point 65+. Wind SW up to 10 MPH.
TUESDAY: Variably cloudy. Early-day showers and a possible thunderstorm. Showers and thunderstorms becoming more likely during the afternoon. Highs 83-90 except cooler South Coast / Cape Cod. Dew point climbs to 70+. Wind SW 5-15 MPH, higher gusts.
TUESDAY NIGHT: Potential showers and thunderstorms early, then clearing. Patchy ground fog. Lows 61-68. Dew point falls toward 60. Wind shifts to NW 5-15 MPH.
WEDNESDAY: Mostly sunny. Highs 81-88. Dew point in 50s. Wind W 5-15 MPH.
WEDNESDAY NIGHT: Mostly clear. Lows 61-68. Dew point in 50s. Wind W up to 10 MPH.
THURSDAY: Mostly sunny to partly cloudy. A shower or thunderstorm possible in the afternoon mainly northern MA and southern NH. Highs 82-89. Dew point returns to around 60. Wind W 5-15 MPH.
THURSDAY NIGHT: Clearing. Lows 58-65. Dew point falls below 55. Wind NW 5-15 MPH.
FRIDAY (INDEPENDENCE DAY): Sun and passing clouds. Highs 77-84. Dew point 50s. Wind NW 5-15 MPH.
DAYS 6-10 (JULY 5-9)
Leaning toward dry weather for the July 5-6 period to finish the weekend, then a disturbance to bring higher humidity and shower / thunderstorm chances early next week. A lot of fine-tuning to do with this forecast. Temperatures near to above normal.
DAYS 11-15 (JULY 10-14)
Large scale pattern evolution looks similar to a pattern we’ve seen a lot in recent weeks – upper level low pressure southeastern US with high pressure to the north. Right now looks like high pressure would be dominant here with fair and seasonable weather overall, but could be some larger temperature contrasts coast vs. inland depending on specifics. Much too soon to try to sort those out on a daily basis.