Boston, MA – Sweltering heat will put nearly all of Southern New England under dangerous conditions Tuesday as temperatures soar past triple digits. In Boston, the heat index could reach 109°F by mid-afternoon, prompting warnings from the National Weather Service to avoid outdoor activity and check on vulnerable neighbors.
According to the NWS office in Norton, an Extreme Heat Warning remains in effect until 8 p.m. Tuesday, covering most of Massachusetts and Rhode Island. Tuesday’s high in Boston will reach 103°F, with minimal overnight relief. Humidity levels will keep heat index values dangerously elevated across Suffolk, Norfolk, and Middlesex counties.
Public health officials advise residents to stay hydrated, remain in air-conditioned spaces, and limit sun exposure—especially during peak afternoon hours. Cooling centers across Boston will be open throughout the day. Emergency crews are on alert for signs of heat stroke, which can develop quickly in these conditions.
Areas along I-90 and I-93 will feel the brunt of the heat wave, with pavement temperatures soaring above 120°F. MBTA services will run on a modified schedule due to heat-related delays.
While a slight cooldown begins Wednesday, highs will still hit 90°F before chances for rain return later in the week.
Five-Day Forecast for Boston, MA (June 24–28):
- Tuesday: Hot, high of 103°F. Heat index up to 109°. Light wind, sunny.
- Wednesday: High near 90°F. Chance of PM showers. Slightly cooler at night (low of 66°F).
- Thursday: Mostly cloudy, high 90°F. 40% chance of showers.
- Friday: Cloudy with PM rain possible, high near 83°F.
- Saturday: Warm and humid, high near 86°F. Showers possible late.
