The Research Triangle area could collect 2 to 4 inches of rain and may see local flooding before a weather system that is settling into the region on Tuesday leaves next week.
It was a gloomy forecast for teachers planning a Wednesday rally in Raleigh for higher pay.
Forecasters at the National Weather Service office in Raleigh put the chance of rain and possible thunderstorms at 30 percent late Tuesday afternoon, and it grows from there to 60 to 80 percent through Saturday.
Temperatures were forecast to be in the low to mid-80s during the day and in the high 60s at night through the weekend.
"We've got some heavier rain working in over the next several days," ABC11 meteorologist Don Schwenneker said.
"I think we'll just see a hit-or-miss shower around today," Schwenneker said. On Wednesday, rain is likely.
"It's going to be a wet day. Teachers heading to the rally, you're going to want to bring lots of rain gear," Schwenneker said.
There will be "lots of heavy rainfall in here Thursday into Friday," he added.
The hazardous weather outlook for central North Carolina said, "Periods of showers and thunderstorms are expected to begin this afternoon and continue through the weekend and into Monday."
"Total rainfall amounts of 2 to 4 inches are forecast, with locally higher totals," the forecasters said.
The weather service's Storm Prediction Center in Oklahoma showed thunderstorms possible for the next several days everywhere from central Pennsylvania to the Gulf of Mexico and from Illinois to the Atlantic Ocean.
The source of all the rain is a low-pressure system that is in the Gulf of Mexico and will work its way across northern Florida and up the Atlantic Coast, forecasters said.