San Jose, at the southern end of the San Francisco Bay, has a Mediterranean climate with around 380 mm (about 15 inches) of rain a year, concentrated almost entirely in the winter months with a long, dry summer typical of coastal California. Because the surrounding hills can intensify incoming Pacific storms, and because much of the South Bay sits on relatively flat, low-lying former marshland, sustained heavy rain, particularly from atmospheric river events, can cause localized flooding along the region’s creeks, as seen during severe flooding in 2017. Because a typical summer week here involves essentially no rain, radar is most useful during the relatively concentrated winter storm season. NWS Doppler radar KMUX (San Francisco Bay Area) covers the region.
Learn more: How Does Rain Radar Work? · Open the full Rain Map