Map: Here’s the timing of the heavy rain and thunderstorms expected in Massachusetts on Friday

 —Jim Davis / The Boston Globe

The heat wave is almost over.

The National Weather Service says a cold front passing over the region Friday will bring relief from the recent searing heat and humidity — as well as heavy rain, gusty winds, and thunderstorms to Massachusetts through the afternoon.

The service has issued a flash flood watch for portions of Massachusetts and Rhode Island, which is in effect through Friday afternoon.

“Showers and thunderstorms will cross eastern Massachusetts and Rhode Island late this morning into late afternoon,” forecasters said of the risk for flooding. “Some of the thunderstorms will be capable of producing very heavy rainfall in a short period of time.”

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The showers and thunderstorms are expected to become more widespread as the day goes on, the service said.

The rain will leave behind much cooler and less humid air than the region has been experiencing in recent days.

“Temperatures won’t be cool, but, with the low levels of humidity and readings well under 90 degrees, it’s going to feel fantastic,” meteorologist David Epstein wrote in his weekend weather forecast.