Boston Faces Upper-70s Monday With Hit-or-Miss Rain as Humidity Returns

Q: Will Sunday’s near-perfect weather give way to just scattered showers, or a truly muggy and stormy start to the week?

Sunday’s excellent weather is expected to give way to a brief muggy, unsettled start to the week, but not an all-out stormy washout. The forecast points to Sunday staying largely dry and comfortable, with highs in the upper 70s to low 80s, low humidity early, and only increasing clouds later. Showers may begin moving in Sunday night, signaling the pattern change. By Monday, the air turns noticeably more humid and less comfortable, with cloudy skies and scattered, hit-or-miss showers. Multiple forecast sources support that setup: not steady rain all day, but periodic showers and some storm chances. Rainfall totals generally look light, and some guidance suggests the steadiest rain would be limited to part of Monday morning before conditions trend mainly dry but cloudy later. The muggy feel is the more reliable part of the forecast. Weather guidance notes that dew points around 60°F or higher begin to feel sticky, with mid-60s and above feeling distinctly muggy. That matches the outlook from Sunday night into at least Tuesday, and likely through Wednesday, when temperatures rise back toward the 80s. So the shift is more than just a few passing showers: early week will feel warmer, cloudier and noticeably more humid. But it still does not look like a prolonged, severe, or nonstop storm pattern. Expect a short unsettled stretch with scattered rain chances and muggy air, followed by drier and more comfortable conditions returning later in the week.

Q: Why can temperatures near 80 feel comfortable one day and sticky the next, and how long will the humid stretch last?

Temperatures near 80 can feel comfortable one day and sticky the next because the key difference is not the air temperature alone, but how much moisture is in the air. Meteorologists look most closely at dew point for that. When dew points are in the 50s to around 60, air usually feels pleasant and sweat can evaporate efficiently, helping the body cool itself. Once dew points rise above 60, the air starts to feel muggy, and in the mid-60s to 70s it can feel distinctly sticky or oppressive. That is why Sunday’s upper 70s to low 80s should still feel comfortable: the air remains relatively dry through much of the day. By Monday, similar temperatures will feel warmer and less comfortable because more humid air moves in. The higher moisture content slows the evaporation of sweat, so the body does not cool as well even if the thermometer reads about the same. The humid stretch looks brief rather than prolonged. Moisture begins increasing Sunday night, with muggy conditions most likely Monday through Wednesday. Thursday may still carry some humidity along with storm chances, but by Friday the forecast calls for lower humidity, cooler upper-70s highs, and a drier, more comfortable feel. Next Saturday is also expected to stay seasonably mild and dry. So the sticky period should last roughly four days, from late Sunday night into Thursday, with the most noticeable discomfort early to midweek.

Q: If no day is a total washout, which parts of the week are actually safest for outdoor plans?

The safest windows for outdoor plans are Sunday during the day, Wednesday, Friday and next Saturday, with Sunday and Friday offering the most comfortable air. Sunday stands out as the best immediate option. The forecast calls for a bright, cool start, highs in the upper 70s to low 80s, and conditions dry enough for most daytime plans. The main caveat is timing: clouds increase later, and showers may arrive Sunday night, so evening events carry more risk than afternoon ones. Monday is the least reliable stretch for outdoor activities. It is not expected to be a washout, but cloudy skies, spotty rain and rising humidity make it the day most likely to interrupt plans. Tuesday looks somewhat better, with partial sun and near-80 temperatures, but the air remains muggy and some supporting forecasts suggest isolated storm potential could linger into Tuesday. Wednesday appears safer than early week because it is forecast to be brighter and dry, even though it will feel warmer, with highs in the mid-80s. Thursday is a step down again because storm chances return. By Friday, conditions improve notably. Forecasts point to lower humidity, a mix of sun and clouds, and highs in the upper 70s, making it one of the best late-week choices. Next Saturday also looks dry and seasonably mild, so it is another strong option for outdoor plans. If comfort matters as much as rain risk, Sunday daytime and Friday are the best overall bets.

3 articles · Updated · Boston News, Weather, Sports | WHDH 7News · Aug 15

Monday in Boston is set to turn gray and more humid, with hit-or-miss rain and highs held to the upper 70s.
Sunday stays the pick of the stretch: a bright, cool start, clouds building later, highs in the upper 70s to low 80s, and humidity still low.
Sunday night brings increasing clouds and spotty showers, setting up the damp, less comfortable feel that lingers through Monday.
Tuesday dries out again with partly sunny skies and low 80s, before storm chances return Thursday and a cooler, less humid Friday follows in the upper 70s.