Forecasters expect a calm, summery Monday across Massachusetts, but the respite will be short-lived: a powerful ridge of high pressure moving east will bring a rapid increase in temperatures and humidity beginning Tuesday, prompting the National Weather Service to issue a Heat Advisory for most of the state.
What to expect this week
Surface highs across southern New England are forecast to reach the mid-90s on Tuesday and again Wednesday, while dew points climb toward 70 degrees. The combination of high heat and humidity will push apparent temperatures, or heat index values, well above the actual air temperature.
"The combination of intense heat and high humidity will make conditions feel significantly hotter than the actual air temperature," National Weather Service forecasters wrote.
The advisory covers most of Massachusetts except Cape Cod, the Islands and the eastern slopes of the Berkshires. It begins at 11 a.m. Tuesday and remains in effect until 8 p.m. Wednesday. Overnight lows Tuesday night are expected to remain elevated — in the mid-70s to near 80 in some locations — limiting nighttime relief and compounding heat stress into Wednesday.
Who is most at risk
Forecasters warned the event still poses significant health risks, particularly for people who work or exercise outdoors, older adults, young children and anyone without access to cool, air-conditioned spaces. Local public-health officials typically advise limiting strenuous outdoor activity during the hottest hours, staying hydrated and checking on vulnerable neighbors.
- Heat Advisory window: 11 a.m. Tuesday to 8 p.m. Wednesday
- Expected highs: mid-90s across much of southern New England
- Overnight lows: mid-70s to near 80 in some areas
Short-term outlook and relief
Isolated, non-severe showers are possible Monday afternoon in northern and western parts of the state as a weak disturbance moves through, but those storms are not expected to significantly alter the overall warming trend. A weather system dropping south from Quebec is forecast to shift the pattern by late week; forecasters say cooler air should filter in by Thursday and Friday, returning highs to the low- to mid-80s across most of Massachusetts by Friday, with the Connecticut River Valley — including Springfield — possibly remaining a few degrees warmer.
| Area | Advisory status | Timing |
|---|---|---|
| Most of Massachusetts | Heat Advisory | 11 a.m. Tuesday — 8 p.m. Wednesday |
| Cape Cod, Islands, eastern Berkshires | No advisory | — |
Local emergency managers and health departments typically open cooling centers during multi-day heat events; residents should check municipal websites or call local health departments for locations and hours. Employers and event organizers should plan for shaded rest areas, frequent breaks and ready access to water for outdoor workers and participants.
While forecasters said this heat wave is not expected to match the intensity of earlier events this summer, its combination of high daytime temperatures and warm nights raises the risk of heat-related illnesses. Residents are advised to stay informed through the National Weather Service and local authorities as conditions evolve.
