Widespread rainfall expected on Thursday as temperatures fall across Mass.

Massachusetts should see much cooler conditions on Thursday after days of oppressive heat and humidity, but forecasters warned that heavy rains could cause localized flooding.

Temperatures in Boston, Worcester and Springfield are expected to hover around 78 on Thursday, a day after all three cities flirted with record highs for July 30, according to the National Weather Service.

A Flood Watch is in place for much of Connecticut, though it could be expanded to include parts of Massachusetts as the day goes on. The strongest thunderstorms are expected to remain southwest of the Bay State, but there is enough humidity in the air that any storms that do form could produce heavy rainfall, forecasters warned.

Conditions will remain mainly dry early Thursday morning, but showers could “develop at just about any time.”

“Most areas should be raining by early to mid-afternoon, with perhaps the Cape and Islands not really getting into much rainfall until late today,” forecasters wrote.

Most areas should see up to 2 inches of rain by Friday morning, with a potential for 4 inches to fall in some areas.

Temperatures on Thursday night and throughout the day Friday are expected to be below normal for late July and early August ahead of a seasonably cool weekend.

“The weekend is shaping up to be nearly perfect weather-wise as high pressure builds in from the north, ushering in dry and seasonable conditions with mostly sunny skies,” forecasters wrote.

High temperatures on Saturday should reach the mid-70s to low-80s, with light wind. Dewpoints in the upper 40s to mid-50s will make it feel very comfortable, forecasters wrote.

Temperatures warm up slightly on Sunday to the low to mid-80s.

Early in the work week, temperatures should stay in the 80s, with dewpoints around 60. No rain is expected until late in the week.