Boston started Monday under clear skies and a cool morning, roughly 64°F at Logan, and should see a sunny, seasonable day with a high near 81°F. Seabreezes will keep immediate waterfront neighborhoods a few degrees cooler while inland spots warm into the upper 70s. The quiet start will not last, though, as a strengthening southerly flow midweek is set to crank up winds and trigger a Gale Watch for coastal waters on Tuesday into Wednesday.
Afternoon And Tonight
Sunny conditions dominate Monday afternoon with southwest winds around 5–10 mph and a high near 81°F. A light seabreeze should shave a few degrees along the harbor and shoreline this afternoon. Overnight, skies stay mostly clear with a low around 65°F and south winds of 6–10 mph. It should remain generally dry, but humidity will start to creep up ahead of the midweek system.
Midweek Marine Watch And Storm Risk
The Gale Watch headlines the midweek forecast. Coastal waters are expected to see strengthening southerly winds Tuesday afternoon, July 21, 2026, through Wednesday evening, July 22, 2026, with gusts potentially reaching gale force and seas building to as high as 12 feet on the outer southern waters. Showers and thunderstorms will increase late Tuesday into Wednesday, with some locations, especially the south coast and Cape Cod, facing soaking downpours and localized rainfall around a half to three-quarters of an inch. A limited risk of stronger storms exists overnight into Wednesday. Mariners, beachgoers and anyone with waterfront plans should prepare for rough, choppy conditions and high surf. According to the National Weather Service Boston/Norton, these hazards will be concentrated Tuesday night into Wednesday as the front moves offshore.
What To Expect And How To Plan
If you have a boat or waterfront event, avoid exposed waters Tuesday and Wednesday and check closely with local marine forecasts before heading out. Small craft operators should be especially cautious and consider staying tied up. Commuters should pack an umbrella for the Tuesday night and Wednesday morning window, since brief heavy downpours could make roads slick, and should expect gusty southerly winds that may affect bridges and exposed corridors. For context on the week's flip from hot to unsettled, see mid-July heat.
