Boston Weather: NWS warns of 12-foot waves, splash-over

Boston weather carried a coastal flooding advisory along the entire Massachusetts shoreline early this week, with 12-foot waves in Boston Harbor raising the chance of splash-over. The National Weather Service also issued specific warnings for Nantucket, where Easy Street may see splash-over and pockets of shallow flooding.

Forecasters said up to a foot of storm surge could push water into exposed parts of Cape Cod and the Islands. Rain was mostly expected to move out by 9 a.m., though a lingering chance of thunderstorms remained.

Nantucket and Cape Cod

The island warning centered on Nantucket, where forecasters said Easy Street may be subject to splash-over. They also said minor coastal flooding could affect Cape Cod and the Islands early this week. The advisory covered the entire coastline of Massachusetts, not just the most exposed stretches.

That wider coverage leaves more of the coast watching the same tide cycle. In Boston Harbor, 12-foot waves could add to splash-over concerns even where floodwater stays shallow.

Wednesday Night Forecast

Temperatures were expected to reach the mid-80s through the day, with sunny and warm conditions Tuesday and into Wednesday. Winds were expected to be calm overnight.

Forecasters were then eyeing a round of thunderstorms and showers to hit the Cape starting Wednesday night and continue to the end of the week. For anyone on the coast, the practical shift is from a morning flood concern to a late-week wet stretch that could keep shoreline conditions changing again.