An upper level high pressure system over the Desert Southwest led to hot temperatures across Southern California from August 1st through 5th, along with areas of dense fog near the coast on August 1st.

Excessive Heat in ORANGE COUNTY INLAND, CALIFORNIA
From 02-AUG-21 08:00:00 to 05-AUG-21 20:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Some areas reached near 100 degrees on August 2nd with 90s thereafter.

Excessive Heat in SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS - THE INLAND EMPIRE, CALIFORNIA
From 02-AUG-21 08:00:00 to 05-AUG-21 20:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Hot temperatures occurred where Ontario and Riverside ASOS sites reported 104 degrees on the 2nd and San Jacinto reported 108 degrees on the 4th of the month.

Excessive Heat in SAN GORGONIO PASS NEAR BANNING, CALIFORNIA
From 02-AUG-21 08:00:00 to 05-AUG-21 20:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Hot temperatures between 105 and 110 degrees occurred.

Excessive Heat in APPLE AND LUCERNE VALLEYS, CALIFORNIA
From 02-AUG-21 08:00:00 to 05-AUG-21 20:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Hot temperatures between 105 and 110 degrees occurred.

Excessive Heat in SAN BERNARDINO COUNTY MOUNTAINS, CALIFORNIA
From 02-AUG-21 08:00:00 to 05-AUG-21 20:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Hot temperatures between 85 and 95 degrees occurred.

Excessive Heat in RIVERSIDE COUNTY MOUNTAINS, CALIFORNIA
From 02-AUG-21 08:00:00 to 05-AUG-21 20:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Hot temperatures between 90 and 95 degrees occurred. Idyllwild recorded a high of 93 on the 3rd and 4th of the month.

Excessive Heat in COACHELLA VALLEY, CALIFORNIA
From 02-AUG-21 08:00:00 to 05-AUG-21 20:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Very hot temperatures over 115 degrees occurred. Both Palm Springs and Thermal ASOS sites hit 122 degrees on August 4th, making it the hottest August temperature on record for Thermal.

Excessive Heat in SAN DIEGO COUNTY DESERTS, CALIFORNIA
From 02-AUG-21 08:00:00 to 05-AUG-21 20:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Hot temperatures over 115 degrees occurred. Borrego Springs reached 119 degrees on the 4th of the month.

Excessive Heat in SAN DIEGO COUNTY MOUNTAINS, CALIFORNIA
From 02-AUG-21 08:00:00 to 05-AUG-21 20:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: RAWS

Hot temperatures between 95 and 105 degrees occurred. Ranchita RAWS hit 105 degrees on the 4th of the month.

Excessive Heat in SAN DIEGO COUNTY VALLEYS, CALIFORNIA
From 02-AUG-21 08:00:00 to 05-AUG-21 20:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Hot temperatures between 95 and 100 degrees occurred. Santee reported a high of 100 degrees on the 2nd of the month.

Dense Fog in ORANGE COUNTY COASTAL, CALIFORNIA
From 01-AUG-21 00:00:00 to 01-AUG-21 10:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Lifeguard

Lifeguard dispatch at San Clemente pier reported visibility of zero on the morning of the 1st.

Dense Fog in SAN DIEGO COUNTY COASTAL AREAS, CALIFORNIA
From 01-AUG-21 00:00:00 to 01-AUG-21 10:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Lifeguard

Lifeguard dispatch reports 1/16 mile visibility at Solana Beach. Other federal observations sites reported visibility under 1/4 mile at times.

Dense Fog in SAN DIEGO COUNTY COASTAL AREAS, CALIFORNIA
From 01-AUG-21 02:30:00 to 01-AUG-21 07:05:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Lowest visibility less than 1/4 mile at KSDM ASOS. Visibility of 1/4 mile or less occurred continuously from 338 am until 805 am.

Dense Fog in SAN DIEGO COUNTY COASTAL AREAS, CALIFORNIA
From 01-AUG-21 01:56:00 to 01-AUG-21 05:56:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Other Federal Agency

Multiple reports (not continuous) of visibility of 1/4 mile between 256 am and 656 am at KNRS. Sum of time periods of 1/4 mile visibility was 2 hours 16 minutes.