An area of upper-level high pressure centered over Southern California brought record-breaking heat across the region April 29th and 30th.
Every event with a place to put it; 9 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS SGX wrote it up.
An area of upper-level high pressure centered over Southern California brought record-breaking heat across the region April 29th and 30th.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS San Diego, CA wrote its last area forecast discussion before the first event at Apr 27, 8:15 PM PST, 3 hours 45 minutes earlier.
Area Forecast Discussion National Weather Service San Diego CA 915 PM PDT Tue Apr 27 2021 .SYNOPSIS... After a cool night tonight, high pressure building over the West Coast will bring a strong warming trend Wednesday through Friday. High temperatures could reach record levels on Friday in some valley, mountain, and desert locations. Over the weekend a trough of low pressure moving inland to the north will bring cooling west of the mountains Saturday, with cooling spreading to the mountains and deserts Sunday. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Showers and isolated thunderstorms rumbled across the San Bernardino and Riverside County mountains and into the Inland Empire this afternoon. There was a total of nine lightning strikes in the Inland Empire. Some of the higher rain amounts today were at Banning with 0.20", the Hemet-Ryan Airport with 0.12", and Wildomar with 0.27". A two-day rainfall summary is headlined on our homepage and also posted on Twitter and Facebook. Significantly warmer days are ahead. A high-amplitude ridge building over the Southwest will bring a warmer day Wednesday. This Santa Ana pattern will bring breezy northeast winds to the San Bernardino mountains, foothills, and parts of the Inland Empire. Highs tomorrow will be 20 degrees warmer than today in the valleys, mountains and deserts, and 5-10 degrees warmer in the coastal zones. Thursday will be warmer than Wednesday, and Friday will be the warmest day of the week in most areas, warm enough to break records, with highs from 95- 100 in the Inland Empire, and from 104-107 in the Lower Desert. The Weekend: It will start to cool a bit west of the mountains Saturday due to the initial effects of the next trough from the northwest bringing stronger onshore flow. The NCEP cluster analysis shows pretty good consistency through the weekend but notable diverging trends in the solutions Mon/Tue of next week mainly due to questions on if another ridge will form off the coast. Most likely that ridge will be weak but could allow temperatures to remain at least a little above normal. Given the time of year (it'll be May starting this weekend) and indications that onshore flow will prevail early next week, we will likely return to coastal night and morning low clouds early next week. && .AVIATION... 280320Z...Coast/Valley/Mountains...FEW with bases 2000-4000 FT MSL across the region. Low confidence in cigs vcty KSAN and KCRQ with bases 1000-1500 FT MSL after 08z Wed. Any low clouds that form will quickly diminish 15-17z Wed. Deserts...SCT clouds AOA 7000 FT MSL, clearing overnight. Breezy W- NW winds turning offshore to the N-NE early Wed morning. N-NE winds gusting 35-45 kts, strongest across mtns and adjacent coastal slopes. MOD up/downdrafts and LLWS possible over and W of the mtns. && .MARINE... No hazardous marine weather is expected through Sunday. && .SKYWARN... Skywarn activation will not be needed this week. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...NONE. && PUBLIC...Moede AVIATION/MARINE...Schenk
The national radar mosaic for the moment the first event began.
8 excessive heat, 1 astronomical low tide. Local standard time, as filed.
The area saw temperatures reach into the 90s to 100 degrees.
The region saw high temperatures from 100-110 degrees.
The region saw high temperatures from 100-110 degrees.
The region saw high temperatures from 95-105 degrees.
The region saw high temperatures from 90-100 degrees.
The region saw high temperatures top out into the low to mid 90s.
The region saw high temperatures top out into the low to mid 90s.
The region saw high temperatures top out into the low to mid 90s.
The area saw temperatures reach into the low 90s away from the coast.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2021Every state in 2021This day in weather historyWarnings in California, April 2021
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 955387, 955388, 955389, 955390, 955391, 955392, 955393, 955394, 955386.