The Brief Southern California is expecting an increase in showers and thunderstorms this week due to rising monsoon moisture. The highest chance for rain and storms will be on Tuesday, particularly in Santa Barbara County. The rest of the week will see a low chance of rain, with the possibility of thunderstorms in the mountains. According to the National Weather Service, there is an increasing chance for showers and thunderstorms this week thanks to the arrival of monsoon moisture in the area. Rain and thunderstorms are likely, especially in Santa Barbara County, where the most moisture will be.