An upper level area of high pressure caused very hot daytime temperatures to occur in late August 2023. It also caused the daily marine layer low clouds/fog to become more confined to the coast, which resulted in dense fog impacting San Diego International Airport for an extended period of time, resulting in a large number of delays.

Excessive Heat in SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS - THE INLAND EMPIRE, CALIFORNIA
From 28-AUG-23 11:00:00 to 30-AUG-23 20:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Very hot daytime temperatures occurred across the Inland Empire August 28-30th, when Excessive Heat Warnings were in effect. Highs between 100-107 occurred each afternoon, with the hottest temperatures occurring near Chino, Riverside, and San Bernardino.

Excessive Heat in SAN DIEGO COUNTY VALLEYS, CALIFORNIA
From 28-AUG-23 11:00:00 to 30-AUG-23 20:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Very hot daytime temperatures occurred across the San Diego County Valleys on August 28-30th, when Excessive Heat Warnings were in effect. Highs between 94-106 degrees occurred each afternoon, with the hottest temperatures occurring near Escondido, Ramona, and Poway.

Excessive Heat in COACHELLA VALLEY, CALIFORNIA
From 28-AUG-23 11:00:00 to 30-AUG-23 20:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Very hot daytime temperatures occurred across the Coachella Valley on August 28-30th, when Excessive Heat Warnings were in effect. Highs between 108-118 degrees occurred each afternoon, with the hottest temperatures occurring in Palm Springs.

Excessive Heat in ORANGE COUNTY INLAND, CALIFORNIA
From 28-AUG-23 11:00:00 to 30-AUG-23 20:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Very hot daytime temperatures occurred across inland portions of Orange County on August 28-30th, when Heat Advisories were in effect. Highs between 91 and 103 degrees occurred each day, with Yorba Linda and Anaheim seeing the hottest temperatures, both exceeding 100 degrees on the 28th and 29th.

Excessive Heat in SAN BERNARDINO COUNTY MOUNTAINS, CALIFORNIA
From 28-AUG-23 11:00:00 to 30-AUG-23 20:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Very hot daytime temperatures occurred across the San Bernardino County Mountains on August 28-30th, when Heat Advisories were in effect. Highs in the upper 80s to near 90 degrees occurred, with Wrightwood and Lake Arrowhead seeing the warmest temperatures.

Excessive Heat in RIVERSIDE COUNTY MOUNTAINS, CALIFORNIA
From 28-AUG-23 11:00:00 to 30-AUG-23 20:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Very hot daytime temperatures occurred across the Riverside County Mountains on August 28-30th, when Heat Advisories were in effect. Highs in the lower 90s to just over 100 degrees occurred, with Anza and Idyllwild seeing the warmest temperatures.

Excessive Heat in SAN DIEGO COUNTY MOUNTAINS, CALIFORNIA
From 28-AUG-23 11:00:00 to 30-AUG-23 20:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Very hot daytime temperatures occurred across the San Diego County Mountains on August 28-30th, when Heat Advisories were in effect. Highs in the lower to middle 90s occurred, with Julian seeing the warmest temperatures.

Excessive Heat in SANTA ANA MOUNTAINS AND FOOTHILLS, CALIFORNIA
From 28-AUG-23 11:00:00 to 30-AUG-23 20:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Very hot daytime temperatures occurred across the Santa Ana Mountains on August 28-30th, when Heat Advisories were in effect. Highs of 99 to 102 occurred near El Cariso during this time.

Dense Fog in SAN DIEGO COUNTY COASTAL AREAS, CALIFORNIA
From 30-AUG-23 02:50:00 to 30-AUG-23 08:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Dense fog reducing visibility to as low as 1/4 SM occurring from roughly 3:50 AM to 9:00 AM PDT caused numerous delays at San Diego International Airport.

Excessive Heat in SAN DIEGO COUNTY DESERTS, CALIFORNIA
From 28-AUG-23 11:00:00 to 30-AUG-23 20:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Very hot daytime temperatures occurred across the San Diego County Deserts on August 28-30th, when Excessive Heat Warnings were in effect. Highs between 108-115 degrees occurred each afternoon, with the hottest temperatures occurring in Borrego Springs.