San Diego County was met with sudden summer rainstorms and lightning strikes Friday from a bout of monsoonal moisture that would likely produce more through the weekend. The monsoonal weather pattern was bringing warm and muggy weather through the weekend, with the occasional lightning producing -thunderstorm, according to NBC 7 Meteorologist Sheena Parveen. A heat advisory is in effect from 10 a.m. Saturday to 8 p.m. Sunday for the mountains and valleys, where temperatures may be in the mid-80s to upper-90s. The deserts are under an extreme heat warning through Sunday evening. On Friday morning, beachgoers in swimsuits and shorts were met with surprise showers in Solana Beach and La Jolla Shores Friday morning as westward moving storm clouds rolled through San Diego County. Imperial Beach saw about a half-inch of rain. Beachgoers in La Jolla Shores were caught in sudden summer thunderstorms on Aug. 7, 2026. The showers followed overnight lightning strikes that could be seen across the county. Parveen said the thunderstorms would weaken through the weekend for most areas except the mountains and deserts, but bouts were still possible. The chance for light thunderstorms stretches through next Wednesday, according to the National Weather Service. Monsoonal moisture develops in the summer when the winds blow from south to north, picking up moisture from the Gulf of Mexico and Gulf of California. As that warm, moist air rises over the mountains in East San Diego County it begins to cool and condense, forming large cumulonimbus clouds. When the clouds are full of water vapor it starts to rain. A view of lightning from the Manchester Grand Hyatt camera. This story uses functionality that may not work in our app. Click here to open the story in your web browser. ...read more read less