For those relishing in the abnormally warm weather in San Diego, the heat wave is expected to continue as temperatures west of the mountains rise above average levels. Coastal areas have enjoyed the warmth, with temperatures ranging from 64 to 74 degrees, while valleys and inland Orange County have had highs of 72 to 82 degrees.
The NWS San Diego predicts highs of 66 to 70 degrees in the high desert and 78 to 82 degrees in the low desert. However, a cool-down is expected on Sunday, bringing temperatures back to seasonal levels.
Meanwhile, forecast discussions from the same source point to a change in the weather pattern beginning early next week; a trough of low pressure is moving southward across the western United States, causing a cool down and bringing moderate to possibly strong Santa Ana winds from Monday to Wednesday.
According to the Area Forecast Discussion, “A trough of low pressure amplifies and dives southeast through the interior West Sunday and Monday,” indicating that there will be persistent onshore flow on Sunday and that coastal low clouds and fog will return Sunday and Monday mornings. However, offshore breezes today and tomorrow might reach up to 30 mph in the foothills.
Visibility has also been an issue in the mornings around the coast and western valleys, where dense fog has hampered road visibility. The National Weather Service advised care during morning commutes and anticipated that the fog would dissipate as the offshore flow deepened, resulting in generally clear skies by Saturday.
They also add that patches of intense fog will persist this morning, but overall coverage is diminishing. Coastal shallow low clouds have caused issues for aviators, with bases of 200-600 ft MSL and visibility as low as 0-3 SM. Improvements are predicted after clearing between 15 and 17Z.
The upcoming Santa Ana phenomenon raises fire weather concerns, with very low humidity levels projected to drop to 10-20% distance from the coast.
The National Weather Service discussion adds, “Santa Ana winds will move into the area Monday, peak in strength Tuesday morning, and gradually fade through Wednesday” while also indicating that locally critical fire weather conditions may arise due to the combination of low humidity, strong winds, and dry fuels, particularly on Tuesday. Residents in the affected areas should remain cautious during this time and follow any warnings or orders issued by local fire departments and forestry services.