textproduct: San Diego

SYNOPSIS

The tropical air mass of former Hurricane Marie that has brought this hot humid heat wave to the area this week will transition over the weekend with a trough of low pressure bringing drier southwest flow aloft and onshore lower level flow. High temperatures will not be quite as hot today for the coast into the western valleys with the cooling then spreading inland for Friday through Sunday with not much change for early next week. There is still a slight chance of showers and thunderstorms for the mountains for this afternoon.

SHORT TERM (Today through Saturday)

It was a very warm start on Wednesday with low temperatures for coast and valleys mostly in the 70s to mid 80s. High temperatures on Wednesday of 105 to 110 were widespread for inland coastal areas into the western valleys. There was less coverage of thunderstorms on Wednesday with the strongest recorded thunderstorms wind gust to 50 mph at Pauma Creek in the Pauma Valley in San Diego County at 1:40 PM.

As of 3 AM early this morning, temperatures are still in the very warm 70s to mid 80s for the coast and valleys, but are a few to around 5 degrees cooler than 24 hours ago for coastal areas into the western valleys. High temperatures will not be quite as hot for coastal areas into the western valleys today, but still with areas of Major to Extreme HeatRisk for inland coastal areas into the western valleys. High temperatures for today will range from 80s at the beaches to the upper 90s to 108 for the Inland Empire with the lower deserts 110 to 114. High temperatures for the mountains and deserts will be a few degrees warmer than Wednesday.

Cooling will spread inland across all of southwestern California on Friday with the cooling continuing through the weekend. By Saturday, moderate or greater HeatRisk will be mostly confined to the lower deserts. High temperatures on Saturday will range from the mid 70s to lower 80s near the coast to the upper 80s to mid 90s for the Inland Empire with 104 to 108 for the lower deserts. Low temperatures early Saturday morning will be mostly in the 60s and lower 70s for the coast and valleys.

LONG TERM (Sunday through Wednesday)

A low pressure system moving inland through the western states will maintain drier southwest flow aloft. High temperatures on Sunday will be as much as 4 to 8 degrees below average for the Inland Empire. High temperatures on Sunday will range from the mid to upper 70s near the coast to the mid to upper 80s for the Inland Empire with 100 to 104 for the lower deserts. Low temperatures will be mostly in the 50s for the inland valleys with the coast into the western valley in the 60s. Patchy night and morning coastal low clouds will spread into the far western valleys at times.

AVIATION

101130Z...VFR conditions expected across the region through this evening, with SCT-BKN clouds between 10-20 kft. ISO SHRA/TSRA over mountains 19-00Z, with CB clouds based 8-12 kft MSL and tops rising to 30 kft. Localized gusty winds and heavy rain in and near any TSRA. Areas of coastal low clouds and fog will gradually increase after 07Z Friday, with cigs most likely 11-16Z Friday in vcnty KSAN. Bases would be around 800-1000 feet MSL, with vis 3-5SM over higher coastal terrain.

MARINE

No hazardous marine conditions are expected through Monday.

CLIMATE

The high temperature of 112 at Escondido on Wednesday was not only a new record for the date, it tied for the fourth highest daily temperature ever recorded at Escondido with a period of record going back to 1893. It was also the latest calendar date for 112 or higher to occur, later than the 115 on September 6th, 2020 and 112 on September 6th, 2024. The heat index at Escondido on Wednesday was highest at 119 at 1:15 PM with a temperature of 111 and a dewpoint of 68.

The low temperature of 81 at Escondido on Wednesday was also a record for the warmest low temperature for the date, exceeding the previous record for the date of 80 in 1984.

The average temperature for Escondido on Wednesday of 96.5 was the warmest daily average temperature ever recorded at Escondido with records going back to 1893, exceeding the 95 on September 6th, 2020 and July 22nd, 2006.

San Diego has now had high temperatures exceeding 90 for the past four days (95 on the 6th and 7th, 93 on the 8th, and 94 on the 9th). The most recent time that occurred was during 2020 from September 28th through October 2nd. High temperatures of 90 or higher at San Diego for 4 or more consecutive days has now only happened at San Diego 15 times with records going back to 1874. The longest stretch of high temperatures of 90 or higher at San Diego was in 1939 from September 17th-22nd in the heat wave that preceded the tropical storm that made landfall in Long Beach on the 25th.

SKYWARN

Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions.

SGX WATCHES/WARNINGS/ADVISORIES

CA...Extreme Heat Warning until 8 PM PDT this evening for Orange County Coastal Areas-Orange County Inland Areas-San Bernardino and Riverside County Valleys-The Inland Empire- San Diego County Coastal Areas-San Diego County Valleys- Santa Ana Mountains and Foothills.

Heat Advisory until 8 PM PDT this evening for Riverside County Mountains-San Diego County Mountains.

Extreme Heat Warning until 8 PM PDT Friday for Coachella Valley- San Diego County Deserts-San Gorgonio Pass near Banning.

PZ...None.