Boston is heating up fast on Tuesday, May 19, 2026, with Logan-area temperatures already in the low 70s under mostly sunny skies this morning. The afternoon high is expected to reach near 87°F, and southwest winds gusting into the mid-teens should keep the harbor relatively cooler while inland neighborhoods climb toward their hottest readings. With both a Heat Advisory and an Air Quality Alert in play for parts of southern New England, midday through late afternoon is the time to be most careful with outdoor plans.
Afternoon Heat And Ozone
The National Weather Service has issued a Heat Advisory from 11 a.m. Tuesday, May 19 through 8 p.m. Wednesday, May 20, warning that inland heat index values could push into the mid 90s, according to NWS Boston/Norton. The Massachusetts Department of Environmental Protection has also posted an Air Quality Alert for elevated ground-level ozone from 11 a.m. to 11 p.m. Tuesday, and sensitive children and adults are urged to limit prolonged outdoor activity, per MassDEP. For more context on the warming trend and what is ahead, check out our midweek heat wave preview.
Showers And Thunderstorms Wednesday
A few scattered showers could pop up late Tuesday afternoon, but the better bet for wet weather arrives Wednesday as a cold front moves into the region. Forecasters expect showers and thunderstorms to be most likely in the afternoon and evening, and any storm that develops could deliver strong, potentially damaging wind gusts. Outdoor events should have a quick indoor backup plan ready to go.
Coast Cooler, Inland Hottest
Temperatures will vary sharply across short distances. Boston and nearby waterfront neighborhoods are expected to top out in the upper 80s, while inland suburbs and river valleys could surge into the low to mid 90s. The South Coast will stay noticeably cooler because of an onshore wind, with some communities only reaching the mid 70s, and overnight temperatures are not expected to bring much in the way of relief.
Plan Ahead
Hydrate early and often, skip strenuous outdoor work during the peak heating hours between 11 a.m. and 4 p.m., and check in on older neighbors or anyone without air conditioning. If you need a cool spot, head to a public building such as a library or call 311 for local cooling-center information. Coaches and organizers should look at moving practices and events earlier in the day or indoors through Wednesday night.
