Tropical Storm Mario could stir up midweek showers in San Diego County

Clouds come in after a sunny day in San Diego. (Photo by Jennifer Vigil/Times of San Diego) San Diego County is experiencing a warm start to the week before a tropical twist brings a midweek cooldown, according to the National Weather Service. Moisture from Tropical Storm Mario is expected to be pulled into the region, raising the odds of showers and thunderstorms from Wednesday evening into Thursday morning, especially in the mountains and deserts. A low-pressure system off the Southern California coast, combined with lingering heat, could spark isolated showers and thunderstorms that produce rainfall rates of 0.5 to 0.75 inches per hour. Temperatures are expected to run 5 to 10 degrees above average Tuesday before dipping below normal by Friday. Highs Tuesday are forecast to hit 76 to 81 near the coast, 85 to 90 inland, 87 to 92 in the western valleys, 90 to 95 near the foothills, 84 to 91 in the mountains and 100 to 104 in the deserts. Early in the week, the marine layer will thin, giving way to patch – or even absent – coastal clouds by midweek, the NWS said. While Mario’s exact path remains uncertain, forecasters caution that if the system shifts closer to Southern California, rainfall could increase across the region.