Swell Matrix

Area Forecast Discussion

National Weather Service San Diego CA

1245 pm PDT Mon Mar 23 2026

Synopsis

High pressure aloft will maintain high temperatures through Friday from around 10 degrees above average near the coast to 15 to 20 degrees above average for inland areas. Night and morning coastal low clouds and fog will spread into the western valleys at times. Cooling will begin to spread farther inland next weekend, but with high temperatures for next Sunday still 10 to 15 degrees above average in the coastal areas and inland valleys.

Discussion

For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,

This afternoon, Temperatures are near or a little higher than at this time yesterday except in the low deserts and portions of the inland valleys. Overnight, marine layer low clouds and fog had spread into the western portions of the inland valleys likely moderating temperatures.

High pressure ridging over SoCal with a closed upper low off the coast of northern Baja will control our weather through the workweek. The ridge will build over the region through Tuesday as the closed upper low moves to the southwest but by Wednesday the low will move northeastward over SoCal. It will have little impact on conditions at the surface, although there will be minor day-to- day differences in temperature. The ridge will rebuild for Thursday and Friday. The marine layer will play a role in affecting temperatures depending on how far inland the low clouds/fog spread during the nights and mornings and how long it takes for them to lift each morning. The subsidence from the high pressure ridge will keep the marine layer inversion fairly strong so clearing is unlikely to be very early each morning. Daytime high temperatures will range from around 10 degrees above average near the coast to 15 to 20 degrees above average for inland areas. Daily maximum records may be broken or tied in the inland areas but the monthly records are unlikely to be challenged.

For the weekend into early next week, Temperatures will trend lower and marine layer clouds and fog will spread farther inland as the high pressure ridge weakens and gets displaced to the southeast as a low pressure trough approaches the coast from the west. Next Monday will likely be the coolest day, with high temperatures mostly 5-10 degrees above seasonal averages.

Aviation

231800z, Low clouds based 500-800 feet MSL return to the coastal areas after 04Z, moving 15 miles inland overnight. Vis 2-4 SM over coastal highlands, patchy areas of 5-6 SM for the general coast. Low clouds clear to beaches 17-18Z Tue. Otherwise, mostly clear and VFR conditions will prevail into Tuesday.

Marine

No hazardous marine conditions expected through Friday.

Watches, Warnings, Advisories

Ca, None. PZ, None.

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