San Diego is amid a significant warm-up, with inland areas experiencing temperatures up to 20 degrees above the average. Today and Friday are expected to be especially hot, with Friday's coastal temperatures potentially reaching up to 81 degrees, while the inland valleys may see highs ranging from 83 to 91 degrees. Mountain areas are not far behind, with projections between 71 and 81 degrees, as reported by the National Weather Service San Diego.
The heat results from high pressure aloft that will peak today and tomorrow. The mountains, deserts, and inland valleys, usually enduring a milder Spring, are now trapped in a high-pressure cauldron. A "Dense Fog Advisory" further complicates matters, in effect until 9 AM PDT for the coastal areas, as outlined by the National Weather Service. The forecast discusses a shallow marine layer along the coast and dense fog that may extend into valley regions Friday night into Saturday morning, with potential visibility dropping to 1 nautical mile or less.
Relief from the uncharacteristic heat is in the offing, though. A shift is on the horizon for the weekend, with Saturday expected to cool down by 4 to 8 degrees compared to Friday, according to information from the Area Forecast Discussion by the NWS San Diego. As the high pressure aloft eases and onshore flow strengthens, a more familiar marine layer is anticipated to deepen, bringing night and morning coastal low clouds into the valleys.
The cooling trend will continue into the middle of next week, with Wednesday's highs potentially dropping 5 degrees below average for western valleys and inland coastal areas. Meanwhile, the deserts will remain about 5 degrees above average, with lower desert areas reaching the upper 80s to lower 90s. A more widespread presence of low clouds and fog at night and in the morning is also expected to spill into portions of the valleys. The San Diego weather is turning, with night and morning marine layer clouds expected to reach further inland than just the beaches, inviting some much-needed temperature moderation after a scorching week.
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