San Diego has a Mediterranean climate similar to Los Angeles, averaging only around 260 mm (about 10 inches) of rain a year, concentrated almost entirely in the winter months with a long, reliably dry summer. Because rain is so infrequent, sudden winter storms, particularly atmospheric river events that can pull tropical moisture up from the Pacific, can cause disproportionate flooding and mudslides on hillsides and canyons not built for heavy runoff. The city’s many canyons and washes can fill quickly during these rare but intense events. Because a typical week here involves no rain at all, radar becomes especially useful during the relatively rare unsettled winter spells. NWS Doppler radar KNKX (San Diego/Miramar) covers the region.
Learn more: How Does Rain Radar Work? · Open the full Rain Map