Fair and cooler weather was in store for San Diego County Sunday, while onshore winds were likely to strengthen through Tuesday, becoming strong and gusty over the mountains and deserts as a storm moves in from the north, the National Weather Service said.
Scattered, light showers could develop as early as Monday, but will be more widespread later Tuesday through Wednesday, with low elevation snow in the mountains, the NWS said.
Clouds and fog impacted coastal areas Sunday morning, with some areas reporting dense fog under one-quarter of a mile. These clouds were forecast to continue to dissipate through the morning, providing another day of mostly sunny skies.
High temperatures along the coast Sunday were predicted to be 63 to 68 degrees with overnight lows of 47 to 52. Valley highs will be 66 to 71, with overnight lows of 41 to 49. Highs in the mountains were expected to be 61 to 68 with overnight lows of 34 to 40, and highs in the deserts will be 78 to 83 with overnight lows of 47 to 55.
"High confidence continues for gusty winds across the mountains, hence our newly advertised high wind watch from Monday morning through late Tuesday night for San Diego County deserts and mountains," forecasters said.
Peak gusts in the wind-prone pass and foothill areas could reach 70 mph at times and 60 mph over the deserts, with considerable blowing dust.
"The headliner in this series will come Tuesday night into Wednesday as a strong shortwave digs south along the California coast, dragging a dollop of cold, Canadian air with it," the NWS said. "The cold air aloft will destabilize the atmosphere further, resulting in widespread showers and possible thunderstorms."
The snow level was predicted to fall to around 3,000 feet by Wednesday morning, likely enshrouding all of the mountains in winter storm conditions. Fog, blowing snow and slippery roads were expected to make travel hazardous, even in the lower passes.
Wednesday was expected to be the coldest day of the week when high temperatures are expected to be some 15 to 20 degrees below normal. High temperatures were not expected to return to average until the end of the week.
No hazardous marine conditions were expected through Monday evening. Strong west-northwest winds 20 knots or more and large, choppy seas were predicted to develop late Monday night. Winds were likely to strengthen Tuesday and Wednesday with gusts 25 to 30 knots. These winds and seas may cause hazardous conditions for small vessels.
Short-period wind swells from the northwest could bring elevated surf at times Monday through Wednesday, mainly on west-facing beaches of southern San Diego County. High rip-current risk may accompany the surf at all San Diego County beaches during this time. Surf will peak at about 6 feet on Tuesday in southern San Diego County.