A severe thunderstorm with “quarter-size” hail could be headed to central Fairfield and New Haven counties Monday afternoon.

The National Weather Service issued a hazardous weather outlook throughout southern Connecticut. The advisory is in effect until 4 p.m. on Monday.

The storm was last spotted in Naugatuck around 3:05 p.m. and heading southeast, the NWS said.

“Frequent cloud to ground lightning is occurring with this storm. Lightning can strike 10 miles away from a thunderstorm. Seek a safe shelter inside a building or vehicle,” the NWS said in its advisory.