Sunday May 18 2025 Forecast (7:42AM)

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DAYS 1-5 (MAY 18-22)

Stacked low pressure (low pressure surface and aloft over the same area) will drift east southeast from Ontario / Maine to southern Atlantic Canada and the adjacent Atlantic Ocean through Monday, wandering away Tuesday as a weak ridge of high pressure builds in. The low pressure area will impact our weather through Monday with cooler, less humid air, lots of clouds, and a few passing showers – although most times will be rain-free in any given location. One detail to note: If you walk outside this morning, especially while there is still enough sun around, it will feel quite mild. This is because a surface occluded front that moved through overnight did not introduce a big change in air mass, only a modest one. The dew point has only dropped slightly, along with the temperature, but during the day today the former will continue to drop while the latter rises very little. This, combined with eventual abundant cumulus and stratocumulus cloud cover, will have the net effect of a cool-down, of course augmented by an increasingly gusty breeze on the back side of low pressure. This will set us up for a continuation of the dominant cloud / interval of sun type of sky on Monday, when a few additional passing showers are possible, along with a cool, gusty breeze. Yesterday, I felt a bit more optimistic about a sunnier Tuesday, but today, not so much. A forecaster can be lead astray by guidance that is showing things moving along too quickly in comparison to what actually happens. Yesterday, I had hopes that high pressure would overtake the region Tuesday enough to keep cloudiness away, but it appears that our region will still be close enough to upper level low pressure and resultant cool air above us that we will still have quite a few stratocumulus clouds about. This time, however, I can confidently keep the shower threat out of the forecast – so expect a dry day Tuesday, despite the lack of full sun. We’ll also see a breeze, though not as gusty as Monday, and cool conditions. So now you think, “ok, we paid our dues with this upper low, right? and it has to warm up and be nice next, right???” … Sorry, not correct. Our next low pressure area in the hybrid progressive / blocking pattern (high pressure eastern Canada, low pressure to the south), arrives at midweek. While there are some guidance differences, the general idea is a slightly elongated low pressure area will move our way via the Ohio Valley and Mid Atlantic, spreading its cloud shield into the region on Wednesday. Rain follows, along with a robust onshore flow and very cool air. This is likely to continue through Thursday, though there are some questions as to how deeply into the rain shield we end up. A little stronger high to the north could suppress the low far enough south for a lighter rainfall event. If this is not the case, a healthier soaking rainfall occurs – a May nor’easter of sorts – certainly not unprecedented but not something we see every year late in the 3rd month of meteorological spring. One definite silver lining, this likely event along with recent events continue to combine to reduce the drought / abnormally dry conditions that have affected the region for quite some time. I’ll continue to fine-tune the midweek forecast the next few days…

TODAY: Cloud / sun mix before clouds becoming dominant. A passing shower is possible any time this afternoon / early evening, favoring I-90 northward. Highs 62-69. Wind W to NW 5-15 MPH, gusts 20-25 MPH.

TONIGHT: Mostly cloudy. Lows 46-53. Wind NW 5-15 MPH and gusty.

MONDAY: Lots of clouds / intervals of sun. A passing shower possible. Highs 61-68. Wind NW 10-20 MPH, gusts as high as 30 MPH.

MONDAY NIGHT: Variably cloudy. Lows 45-52. Wind N 5-15 MPH, gusty.

TUESDAY: Limited sun / lots of clouds. Highs 59-66. Wind N to NE 5-15 MPH.

TUESDAY NIGHT: Considerably cloudy. Lows 46-53. Wind NE up to 10 MPH.

WEDNESDAY: Cloudy. Rain arriving southwest to northeast by late-day. Highs 53-60, coolest coastal areas. Wind NE to E 5-15 MPH.

WEDNESDAY NIGHT / THURSDAY: Overcast. Rain likely. Areas of fog. Temperatures fall to 45-52 then steady. Wind E to NE 10-20 MPH, higher gusts especially in coastal areas.

DAYS 6-10 (MAY 23-27)

Improving weather but still cool with a possible shower on May 23 as low pressure moves away. Gradually weakening upper level low pressure over the region during the Memorial Day Weekend (May 24-26) – this would promote a daily chance of showers and a few thunderstorms but also many dry hours. Another low pressure area may bring a general rainfall back by the end of the period. Temperatures run below normal in the expected pattern.

DAYS 11-15 (MAY 28 – JUNE 1)

A low pressure dominated cool and unsettled pattern transitions to a drier and more progressive northwest flow pattern as we head through the final days of May toward the start of June.

46 thoughts on “Sunday May 18 2025 Forecast (7:42AM)”

  2. GFS hinting at a tropical system in the western Caribbean around June 1. A few Ensemble members also show it. Meanwhile, nothing in the ECMWF, but a few ECMWF Ensemble members show something in the Gulf around then.

    2. I won’t trust the GFS much for a while. Will be interesting to watch the trend there. June 1, after all, is the start of Hurricane season!

  9. Thanks, TK.

    Beautiful morning, though it seems the pollen count is high. Autoimmune dysfunction is highly individualized. It feels to me like this year’s allergies are worse than normal. Have others experienced similar symptoms?

    4. My son has had a tough few weeks with allergies. Much worse than he has experienced other years.

    5. Mine are about average. The pollen season ran a bit early due to a mild March & April, and there was some overlap with trees that usually stagger their pollen peaks. So the net result was a period of time where many people who were affected by more types of pollen noticed a worse than typical and early-hitting season.

    6. When younger, I’d have mild symptoms around the time the lilacs bloomed. I never had asthma. I do now and it mixes with what seem to be more allergies. It was really bad but I have a new steroid inhaler that seems to be helping……one that is actually not well over $100.

  11. Wayyyyyyyy off weather topic.

    Has anyone seen Argo? I have not because I know it stays but thought I’d give it a try on a quiet Sunday afternoon. There seems to be a number of movies named Argo. Is the one with affleck the original??

  12. Thanks for chiming in, WHW friends, on my question related to this year’s allergy season. I’m doing fine, now. Zyrtec (cetirizine) is my go-to medicine.

  14. So much for the “energy” I predicted the Sox would get from last night’s win. They’re getting clobbered today. Something isn’t right with the team. Does Breslow see it, though? Or is he too detached? On paper, they’re better than this. But that’s theoretical. It starts and ends with pitching. That’s where even on paper, they’re not that good. If I were the GM, I’d look to trade for top (not middling) relief AND starting help. They have some minor league chips to use and a player or two on their major league roster. They’re not going to be close to serious contenders with the current rotation and bullpen.

    1. After last night, some fans though we were a lock for the World Series. 😉

      It’s a long season – ups and downs. Like I said several times, they’ll be similar to, but a little better than last year when it’s all said and done. 🙂

  15. I’m not sure if today offered any clarity for Thursday …. Cloudy/misty/cool or full blown northeaster.

  17. I have a temp rule ……

    The daily high temp > daily solar max sun angle.

    We’ve passed that rule most of this spring, but are going to fail it for a long stretch starting Tuesday.

    By Thursday, the max sun angle in Boston is 68 and the high might be 48. Brutal.

    2. I have a theory about the cost of electricity….keep temps under 55 and cost might be manageable

  18. Watching game 7, Leafs vs Panthers. Both teams playing strong hockey. Crisp, clean and intense. 0-0 after the 1st.

  19. It was a breezy day in NYC today. Celebrated two of my kids graduating Saint John’s this weekend. Great fresh air for an outdoor graduation

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