Heavy rains across region, especially in Bristol and Plymouth counties and Newport, R.I.

A pedestrian slowly walked through a puddle along Mass. Ave. in Cambridge.
A pedestrian slowly walked through a puddle along Mass. Ave. in Cambridge. Jessica Rinaldi/Globe Staff/Globe Staff

The region’s weather picture is changing dramatically Tuesday with sunshine being replaced by glowering clouds heralding thunderstorms, possible localized flooding, and heavy rains especially in southeastern Massachusetts and Rhode Island.

The National Weather Service said Tuesday that Boston should get just over a half inch of rain by the time the system dissipates Tuesday night. But much heavier rains are forecast for coastal Plymouth County, Bristol County and Rhode Island, where Newport could get up to 3 inches of rain.

“Widespread rain with embedded heavy downpours, a few thunderstorms, along with humid conditions,’’ forecasters wrote Tuesday. “The greatest threat will be the potential for localized flooding across south coastal New England, especially across portions of Connecticut, Rhode Island, and southeast Massachusetts.”


Localized flooding is possible, forecasters cautioned.

There is a secondary concern, forecasters wrote. As the rainy weather eases, winds may increase when a new system arrives in the region there is a “very low risk” for a tornado. However, forecasters stress cloud cover may keep temperatures too cool to generate severe wind conditions.

The rainy weather will persist into Tuesday evening, forecasters wrote. But the best of summer returns by mid-week.

“Drier weather developing Wednesday. Scattered showers are possible sometime Thursday into Friday,’’ forecasters wrote. “Otherwise, expecting a high pressure to build over the region with mainly dry, seasonable weather through Monday.”

John R. Ellement can be reached at ellement@globe.com. Follow him on Twitter @JREbosglobe.