SAN DIEGO (CNS) - A heat wave will grip San Diego County this week, attended by an abundance of monsoonal moisture, possibly generating thunderstorms in some areas starting Monday.

A high-pressure system expanding over the southwest region will bring warmer temperatures throughout the week, according to the National Weather Service.

The system will also bring a slight chance of isolated thunderstorms this afternoon in the county mountains and deserts, NWS meteorologist Dan Gregoria said.

RELATED: LATEST FORECAST

That chance will continue in those areas through Thursday, with the best chance of thunderstorms on Tuesday and Wednesday, Gregoria said.

Flash flooding will be possible in those areas if storms develop and portions of the western valleys will also have a slight chance of thunderstorms on Tuesday, according to the NWS.

High temperatures Monday are expected to reach 84 near the coast and inland, 88 in the western valleys, 95 near the foothills, 95 in the mountains and 111 in the deserts.

Temperatures will rise a few degrees in the western valleys on Tuesday, then remain around the same for the rest of the workweek, forecasters said.