Tropical Storm Threatens Historic MA Dry Spell: When It May Rain Again

MASSACHUSETTS — A remarkable stretch of dry weather in which Boston and many other Massachusetts cities and towns have gone nearly a month without measurable rain may be coming to an end this week as a tropical system gathers steam off the coast of the Carolinas.

The last rain total measuring a "trace" or more in Boston was Aug. 20 — making it the sixth-longest dry stretch of all time in Boston, according to the National Weather Service.

Boston is likely to tie for the fifth-longest stretch at 28 days on Tuesday, and maybe the fourth-longest stretch at 29 days on Wednesday before the threat of rain finally returns on Thursday.

The longest dry spell for Boston on record was 44 days in October and November in 1924.

The next few days will continue to feature delightfully warm days and cool nights with highs in the lower 80s and temperatures dropping into the 50s at night — with some 40s in the cooler suburbs.

The weather should make for a great viewing of the full Harvest supermoon on Tuesday night.

While the NWS said there is a "slight" chance of showers Wednesday afternoon, the more meaningful chance of real rain comes on Thursday when a storm currently threatening to turn into a tropical storm in the mid-Atlantic tries to push its way north.

But with high pressure still dominating over Canada, there is no sure thing the rain will make it to New England. The NWS put the chances of rain showers in Boston at 40 percent on Thursday.

That chance continues into Thursday before the dry air is expected to return for the weekend, albeit with much cooler temperatures than this past one.

Friday is forecast to be mostly cloudy with a high near 70 degrees and a northeast wind making it more chilly along the coast.

Saturday and Sunday should finally feel more like fall with mostly sunny skies, highs in the 60s and a brisk easterly wind on both days.

(Scott Souza is a Patch field editor covering Beverly, Danvers, Marblehead, Peabody, Salem and Swampscott. He can be reached at Scott.Souza@Patch.com. X/Twitter: @Scott_Souza.)