DAYS 1-5 (MAY 20-24)

A slow-moving warm front is still traversing our region, as evident by the surface wind, very light but from the east and southeast in the Boston area to southern NH and from the southwest in areas to the south, as well as a pretty extensive blanket of stratus clouds across all coastal areas and even inland for some distance in southern NH and northeastern MA as well. It basically takes the entirety of today for this front to push its way through our area. The high May sun will work on the stratus which should break up in most locations it sits as of the time of this writing. So all in all it’s not to be a bad day, other than contending with some low cloudiness in some areas. Tonight, as the warmer air becomes more established, we’ll have to eye the remains of a mesoscale convective system from the west, as it may bring a batch of at least showers and potentially heavier thunderstorms to parts of southern New England. Short range guidance indicates this favors areas near and south of I-90, but these things are fickle and can be very poorly forecast by short range guidance at times, so tracking it closely will be necessary. I don’t think this is going to be a cause of concern regarding severe weather, but it’s always worth watching just in case. And then the heat is on for the weekend. Things come together at upper levels and at the surface to deliver a 2-day hot spell where many areas will see 90+ for high temps. It’s important to note this will NOT be a heatwave, as you need 3 or more consecutive days of 90+ for that. And this is going to break by Monday. But before that, we’re hot. The usual areas along the South Coast and some East Coast beaches will be cooler though. If you go to the beach, remember that the water temperatures remain very chilly at this time of year (barely to 50 East Coast beaches, and just into the 50s South Coast beaches). You lose body heat rapidly in the water, so be wise about immersion and length of time in there if you decide to brave the chilly water. Humidity will be on the increase this weekend, but we’re starting low, and it will never really get overly oppressive, although the combination of the moderate humidity and early-season heat will make it feel quite uncomfortable for those sensitive to it. A bit of atmospheric irony: There are some conditions that would help initiate explosive thunderstorm development on Saturday, but too many limiting factors including no triggers and a big old cap, so we’re not going to have any storms around at all that day. Sunday, the “perfect” conditions are lost a bit, but so are some of the limitations, so we may see a few isolated air mass storms pop up, but more organized activity will wait until a cold front enters and crosses the region. But the timing of this front is so late that we probably experience a much weakened version of what was stronger to our north and west, and this will come through Sunday night and early Monday. So while Monday may start a bit unsettled, it will be a much cooler day with dry weather returning – temperatures about 20 degrees lower than Sunday, and much lower dew point air moving in after a somewhat humid start. I’m a little nervous about that front not getting that far to the south and a wave of low pressure that may keep it cloudier for more of Monday, and even threatening some showers, but for now staying optimistic with a sun/cloud blend and drier air – just know that my Monday outlook is lower confidence. High pressure to the north will turn the wind northeast by Tuesday and while I expect fair weather, it should be rather cool, especially in comparison to what we had just gone through over the weekend.

TODAY: Mostly cloudy start coastal areas as well as southeastern NH and northeastern MA followed by a sun/cloud mix trending sunnier these areas while other areas that start with sunshine keep it with just a few clouds. Highs 68-75 coast, 75-82 inland. Wind E shifting to S up to 10 MPH eastern MA and southern NH, S-SW up to 10 MPH elsewhere.

TONIGHT: Clouds return. Showers and possible thunderstorms favoring areas near and south of I-90 from west to east late evening / overnight. Patchy fog forming especially behind any shower activity. Lows 58-65. Wind S-SW 5-15 MPH but brief stronger gusts can occur near any thunderstorms.

SATURDAY: Areas of low clouds and patchy fog to start, then turning sunny. Highs 90–97 except 83-90 East Coast beaches and just inland from South Coast, 76-83 South Coast / Cape Cod. Becoming more humid – dew point rising to 60s. Wind SW 5-10 MPH but weak sea breezes possible eastern shores.

SATURDAY NIGHT: Mostly clear. Patchy ground fog. Lows 63-70. Humid – dew point 60s. Wind SW 5-15 MPH.

SUNDAY: Mostly sunny. Only a slight chance isolated afternoon thunderstorms. Highs 91-98, hottest interior valleys, but 84-91 East Coast beaches and just inland from South Coast, and 77-84 South Coast / Cape Cod. Humid – dew point middle to upper 60s. Wind SW 5-15 MPH, but local weak sea breezes eastern shores.

SUNDAY NIGHT: Variably cloudy. Chance of showers and thunderstorms. Patchy fog. Lows 65-72. Humid – dew point 60s. Wind SW 5-15 MPH, higher gusts.

MONDAY: Sun/cloud mix. Chance of a shower early. Highs 75-82. Less humid. Wind W-NW 5-15 MPH.

MONDAY NIGHT: Clearing. Lows 50-57. Wind N 5-15 MPH.

TUESDAY: Mostly sunny. Highs 60-67, coolest coast. Wind NE 10-20 MPH.

DAYS 6-10 (MAY 25-29)

Cool start, fair weather holds May 25 with high pressure to the north. Warmer air attempts a come-back with some unsettled weather possible May 26-27. Drier and warmer weather possible by later in the period which includes the start of Memorial Day Weekend.

DAYS 11-15 (MAY 30 – JUNE 3)

Overall pattern dry, zonal flow, but brief wet weather threats with air mass changes. Temperatures variable, averaging near to slightly above normal.