Boston’s 20-Day Dry Streak Ends Friday With 1–3 Inches of Rain Possible

Boston’s nearly three-week dry stretch is set to break Friday, Nov. 6, as a moisture-rich band brings heavy rain into eastern Massachusetts and a risk of localized street flooding, according to CBS News Boston / WBZ and AccuWeather. The last measurable rainfall at Boston Logan International Airport was 0.44 inches on Oct. 16, weathertotals.com shows from National Weather Service daily climate reports — about 20 days without measurable rain as of Thursday morning, Nov. 5.

CBS Boston said the dry streak is the longest in two years, and that October was the second-sunniest month on record in Boston with just 14% overcast skies. AccuWeather separately described late-week downpours as ending a prolonged dry stretch across much of the Northeast before cooler air arrives for the weekend.

When the rain arrives — and how much

CBS Boston’s Terry Eliasen said scattered showers are possible during the day Friday, with the heaviest rain arriving later Friday afternoon or early evening and continuing after dark through the predawn hours Saturday. The band is expected to exit the coastline by dawn Saturday, leaving mainly cloudy skies and a few scattered showers.

Under the heavy band, CBS Boston put potential rainfall at 1 to 3 inches, with isolated totals of 4 to 5 inches possible. Southeastern Massachusetts — southern Plymouth and Bristol counties, Cape Cod and the Islands — carries the highest risk for several inches. Greater Boston sits on the edge of that heavy corridor; areas north and west of the city are more likely to see less than an inch, and in some cases very little rain at all, CBS said.

The Boston Globe’s Ken Mahan forecast a stalled front favoring southeastern Massachusetts and southern Rhode Island for the highest totals from late Thursday through Saturday morning, with some areas seeing as much as about 2 inches and a low risk of isolated flash flooding from Boston to the Cape. AccuWeather’s Brett Anderson described a narrow coastal corridor of heavy rain and embedded thunderstorms from southeastern Virginia through southeastern Massachusetts, with 1 to 4 inches possible over roughly 24 to 36 hours where the band locks in.

Data analysis: dry streak, October sun and the rainfall deficit

Official climate figures compiled for Boston Logan show October finished at 2.08 inches of rain against a 1991–2020 normal of 4.03 inches — a 1.95-inch, or 48%, shortfall. November had recorded 0.00 inches through Nov. 4 against a 0.49-inch normal for that early stretch. Year to date, Boston has 24.99 inches versus a 36.12-inch normal, an 11.13-inch deficit (about 31%), according to the NWS daily climate series carried by weathertotals.com.

*November normal shown is month-to-date normal through Nov. 4 from the NWS climate report, not the full-month 3.66-inch normal. Source: NWS / weathertotals.com.

WHDH’s weather blog noted on Oct. 29 that Boston was tied for the longest dry stretch of the year at 13 days and that a cold front the next morning offered only a slim chance of a sprinkle — a setup that, in hindsight, left the dry streak intact into early November. CBS Boston’s Friday alert therefore marks the first organized, multi-inch opportunity in weeks.

Because soils and storm drains have been dry for so long, CBS Boston said there is no concern about large river or widespread flooding with this event. The main hazard is localized street and urban flooding where heavier cells stall, plus the usual early-rain slickness AccuWeather flagged from oil and dust on dry pavement and from wet leaves blocking drains.

Warmth before the front

The rain follows a record-challenging warm spell. The Globe reported Boston hit 77 degrees Wednesday, just shy of a 39-year record of 78, and said Thursday was likely to tie the record of four consecutive November days at 70 degrees or warmer (set in 2020 and 2022). AccuWeather’s Joe Lundberg said the rain and cooldown would follow what may be the warmest day in the Northeast until March or April.

For drivers and transit riders, the practical takeaway is Friday night into early Saturday: allow extra travel time, watch for ponding on poorly drained streets, and treat the first wet roads after a three-week dry spell as unusually slick. Our Boston traffic today page tracks road impacts, and the Boston news hub collects related local alerts.

Weekend outlooks from AccuWeather and the Globe point to cooler air after the front, with interior highs more often in the 40s and 50s and showers possible inland. Coastal breaks of sunshine could still push readings into the 50s or lower 60s in spots.

Sources

• CBS News Boston: Dry weather streak ending with heavy rain, localized flooding forecast
• Boston Globe: New England forecast — warm air, weekend rain outlook
• AccuWeather: Late-week downpours to end Northeast dry streak
• weathertotals.com: Boston rainfall totals and NWS climate figures
• WHDH: Dry streak continues for the Bay State (Oct. 29 blog)