Boston is starting Tuesday quietly, but it will not stay that way for long. As of 5:35 a.m. EDT on July 21, Boston Logan was reporting mostly clear skies and about 63°F. Temperatures are expected to climb into the low 80s, and then scattered showers and thunderstorms move back in this evening and last into early Wednesday, July 22, 2026. South winds will pick up this afternoon and tonight, and any stronger storms could trigger brief urban flooding in low-lying or poorly drained spots.
Evening Into Wednesday Morning
Showers may start as a slight chance between 4 and 5 p.m. Tuesday, with odds ramping up this evening and peaking overnight into early Wednesday. According to the National Weather Service Boston/Norton, the chance of showers and thunderstorms jumps to around 90% tonight, with new rainfall of roughly one-half to three-quarters of an inch possible. A few storms could pack damaging wind and very heavy downpours.
The agency has converted an earlier Gale Watch to Small Craft Advisories for southern and outer coastal waters, and it has posted a High Surf Advisory for many south-facing beaches from 6 a.m. Wednesday through 8 p.m. Thursday. Expect reduced visibility and gusty south to southeast winds late tonight into Wednesday morning.
What To Watch For
Drivers should plan for a slower-than-usual evening commute, since heavy downpours can sharply cut visibility and leave standing water on city streets. Beachgoers should follow lifeguard instructions and heed shoreline warnings during the High Surf Advisory, and boaters are better off avoiding exposed waters while Small Craft Advisories are in effect.
We highlighted rising rip-current risks earlier this week in sneaky surf stalks Boston beaches, and that local guidance still applies as surf builds.
Looking Ahead
Rain chances drop on Thursday, July 23, 2026, as high pressure builds in. Expect sunny skies and highs near 80°F with lower humidity into the weekend. Temperatures stay seasonable through Sunday with only isolated chances for showers and lighter winds. Forecasters will keep an eye on Monday for a possible return of unsettled weather early next week.
