Weekly Significant Weather Outlook
Active weather is anticipated for late Tuesday into Wednesday with strong south to southwest winds along the coast and scattered heavy downpours with possible embedded thunderstorms. A robust upper trough will approach New England, and an associated frontal boundary will slowly move through the area Tuesday night into Wednesday.
Southerly winds will increase Tuesday afternoon and become strong in coastal areas Tuesday night into early Wednesday. Gusts to 50+ mph across the Cape and Islands and 40 to 50 mph along the rest of the MA and RI coastline are possible Tuesday night into early Wednesday morning. There could be some scattered tree damage across the Cape and Islands. Although variations exist from model to model, there looks to be a 50 to 60+ knot low level jet that will pass over or near the Cape Tuesday night.
These winds will create especially hazardous conditions for boating late Tuesday through Wednesday, and the National Weather Service has issued a Gale Watch (rather unusual for this time of year). Seas are likely to build to between 10 and 12 feet south of Block Island, Martha’s Vineyard, and Nantucket as well as east of Cape Cod during Tuesday night into Wednesday. The wind generated waves will also produce high surf and dangerous rip currents along south and southeast facing beaches exposed to the open ocean Tuesday evening through Wednesday. A significant swell may linger into Thursday and result in a prolonged rip current risk along south and some east ocean exposed beaches.
The various numerical weather prediction models indicate a very moist and at least marginally unstable environment developing Tuesday afternoon and continuing Tuesday night but vary considerably with respect to the details. Showers and possible thunderstorms will likely spread southwest to northeast across southern New England Tuesday afternoon. Bands of heavy downpours are possible late Tuesday afternoon and night, especially across the Cape and Islands as well as along other portions of the south coast of RI and MA. There is some risk of localized urban flooding in southern RI and southeast MA if multiple heavy downpours impact the same location. Deeper into interior southern New England, one cannot rule out an isolated downpour or two late Tuesday afternoon or Tuesday night especially if the low-level jet should shift a little further north. In the end, highly variable rainfall amounts are expected with the potential for 1 to 2+ inches most likely toward the New England south coast.
There is a slight risk of a severe thunderstorm or two across western MA and western CT Tuesday afternoon/evening (with a higher risk further southwest over portions of NJ, PA, MD, and WV).
Showers, possibly heavy, may linger for a while across the Cape and Islands on Wednesday. Elsewhere, there looks to be the potential for scattered showers and thunderstorms to develop as the region remains under upper-level cyclonic flow and a somewhat moist and unstable atmosphere. Any thunderstorms that should develop could produce strong wind gusts given relatively strong wind flow aloft. Any packet of wind energy (associated with a shortwave trough) rotating about a broad upper-level trough could induce the formation of thunderstorm clusters anywhere in New England during Wednesday afternoon.
The rest of the week (Thursday onward) looks to feature high pressure moving across the area with more tranquil weather except for the risk of lingering rip currents along some beaches on Thursday.
A tropical depression in the northeast Gulf as of Monday morning is projected to intensify into Tropical Storm Bertha and move westward along or just south of the Florida panhandle, Alabama, Mississippi, and Louisiana coasts. The system may eventually move into northeast Texas and slowly dissipate. It is unlikely to have any impact on southern New England, although there’s a small possibility that some of its moisture could get entrained into the upper trough and frontal boundary affecting our area Tuesday night. Although the Gulf coast may be impacted by tropical storm force winds, the greatest impact from Bertha is expected to be heavy rain and pockets of flash flooding along the north Gulf coast area (Florida panhandle west to northeast Texas).
Since this is expected to be the only blog issued this week (due to the author’s travel), please monitor the latest information from the National Weather Service for the latest information on any significant weather this week.
Next Message
There will be no weather blog messages July 21 – 27 due to the author being on travel. The next message will be the weekly significant weather outlook to be issued one day late on Tuesday July 28.
About this Blog and Disclaimer
The National Weather Service monitors the weather 24/7 and updates forecasts, watches, and warnings as necessary. For most of southern New England, refer to your local Weather Forecast Office for the latest forecast/warning information at weather.gov/box. For information from other Weather Forecast Offices, go to weather.gov and click on the location of interest on the map.
The frequency of this blog will depend upon the nature of the weather threat and availability of the author. Thus, for the latest information on weather forecasts and warnings, refer to the National Weather Service, which monitors and forecasts the weather 24/7.
Blue Hill Observatory and Science Center (BHOSC)
The BHOSC maintains a continuous daily observation record that dates from February 1, 1885 without interruption and provides educational information on weather and climate to area students and the community at large. Your support of BHOSC is much appreciated and enables this nonprofit organization to maintain the long-term climate record at the Blue Hill Observatory (longest continuous record in North America) and provide valuable educational resources on weather and climate via outreach to schools, site visits/tours, webinars, and conferences. For more information on the Blue Hill Observatory and Science Center, explore bluehill.org.
Message issued July 20, 2026 by:
Bob Thompson
Retired National Weather Service Meteorologist
Blue Hill Observatory and Science Center Board member
