Thunderstorms on the 2nd and 5th of the month produced heavy rain in some desert, mountain, and valley locations, with isolated rainfall totals over one inch. The remainder of the month was relatively dry.
Every event with a place to put it; 10 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.
Thunderstorms on the 2nd and 5th of the month produced heavy rain in some desert, mountain, and valley locations, with isolated rainfall totals over one inch. The remainder of the month was relatively dry.
California remained in a State of Emergency for the ongoing drought. Water restrictions and voluntary conservation remained in force, as well as water cut-backs for agricultural purposes. On September 17th, the U.S. Department of Agriculture granted a Secretarial disaster designation for many counties in California, including Orange, Riverside, San Bernardino, and San Diego. This was due to agricultural losses caused by drought beginning on January 1, 2009.
The Weekly U.S. Drought Monitor continued a D2 (Severe Drought) for the mountains, valleys, and coastal regions, while the deserts remained in D1 (Moderate Drought).
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 Aug 31, 7:30 PM PST, 4 hours 30 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN DIEGO CA 830 PM PDT MON AUG 31 2009 .SYNOPSIS...UPPER LEVEL HIGH PRESSURE OVER THE SOUTHWEST WILL CONTINUE VERY WARM WEATHER THROUGH MID WEEK...ESPECIALLY INLAND. COOLER BY THE END OF THE WEEK AS THE HIGH WEAKENS. MID LEVEL MOISTURE IN SOUTHEAST FLOW WILL BRING A CHANCE OF THUNDERSTORMS TO THE MOUNTAINS AND DESERTS DURING THE AFTERNOONS THROUGH WEDNESDAY. A REDEVELOPING MARINE LAYER WILL CAUSE COASTAL LOW CLOUDS AND LOCALLY DENSE FOG DURING THE NIGHTS AND MORNINGS. THE MARINE LAYER WILL ALSO MODERATE TEMPERATURES NEAR THE COAST. && .DISCUSSION...FOR SOUTHWEST CALIFORNIA INCLUDING SAN DIEGO... ORANGE...SOUTHWEST SAN BERNARDINO AND WEST RIVERSIDE COUNTIES. THE IR SAT LOOP THIS EVENING SHOWS AREAS OF MID-HIGH LEVEL CLOUDS SLOWLY THINNING OVER THE AREA. SOME OF THIS IS DEBRIS FROM STRONG THUNDERSTORMS THAT DEVELOPED S OF THE BORDER EARLIER THIS AFTERNOON. IT REMAINED QUITE WARM...BUT THE TRENDS WERE DOWN FOR TEMPS AND UP FOR DEWPOINTS...WHICH IS POINTING TOWARD MORE HUMIDITY FOR THE NEXT FEW DAYS. PRESSURE GRADIENT TRENDS WERE WEAK BUT MOSTLY ONSHORE. THE 00Z MIRAMAR SOUNDING STILL INDICATED A DEEP DRY LAYER BTWN 5K AND 15K FT. WINDS WERE NW 15 KT BELOW 7K FT AND S 5-10KT ABOVE. NO MARINE CLOUDS WERE EVIDENT AT 03Z. AS THE HIGHER CLOUDS THIN...THE MARINE CLOUDS WILL HAVE A CHANCE TO DEVELOP OVERNIGHT. SINCE SURFACE OBSERVATIONS ALONG THE COAST INDICATE AN EDDY IS PRESENT...THE CHANCE IS PRETTY GOOD FOR SOME LOWER CLOUDS AND FOG ALONG THE COASTAL STRIP BY MORNING. STRONG UPPER LEVEL HIGH PRESSURE WILL CONTINUE OVER THE SW. WHILE THERE WILL BE SLIGHT COOLING...MAX TEMPS WILL BE WELL ABOVE SEASONAL AVERAGES WITH HOT DAYS INLAND. HOWEVER...A REDEVELOPING MARINE LAYER AND INTERMITTENT COASTAL EDDY WILL MODERATE MAX TEMPS NEAR THE COAST. THE MARINE LAYER WILL BE FAIRLY SHALLOW WITH LOW CLOUDS AND FOG MOSTLY CONFINED TO THE COASTAL AREAS. THERE COULD BE LOCAL DENSE FOG ON THE HIGHER COASTAL TERRAIN. SINCE THE UPPER HIGH HAS SHIFTED E...IT WILL ALLOW LIMITED MOISTURE TO MOVE INTO OUR AREA ON SE WINDS ALOFT. PROVIDED THERE IS ENOUGH HEATING TOMORROW...IT APPEARS THERE WILL BE ENOUGH INSTABILITY FOR THUNDERSTORMS TO DEVELOP. A LIMITING FACTOR WILL BE POTENTIAL CLOUDS AND THE MODERATE SE WINDS IN THE MID-LEVELS. ONCE THE SUB-CLOUD LAYER MOISTENS FURTHER ON TUE... THERE WILL BE AT LEAST A SLIGHT CHANCE OF MEASURABLE RAIN TO REACH THE GROUND IF SOMETHING GETS GOING. THE MOIST MID-LEVEL FLOW CONTINUES UNABATED THROUGH WED...THEN THE UPPER-LEVEL HIGH PRESSURE RIDGE WEAKENS AND SETTLES FARTHER SOUTH AS A LOW PRESSURE TROUGH DEVELOPS S ALONG THE W COAST. SOME RESIDUAL MOISTURE WILL PERSIST ON THU...BUT THE TREND WILL BE FOR DRYING WITH THE RIDGE AXIS OVERHEAD. HURRICANE JIMENA...CURRENTLY 245 MILES S OF CABO SAN LUCAS...IS MOVING NW AT 9 MPH. AT 8 PM PDT...IT IS A STRONG CATEGORY 4 STORM WITH CENTRAL CORE WINDS OF 155 MPH. THIS CYCLONE IS FORECAST TO MOVE ONSHORE OVER THE BAJA PENINSULA...AND THEN MOVE UP THROUGH THE GULF OF CALIFORNIA AND WEAKEN THROUGH THU. AT THIS TIME IS NOT EXPECTED TO IMPACT OUR WEATHER HERE IN SOUTHWEST CA. FOR THE LABOR DAY WEEKEND...THE GFS AND ECMWF MODELS ARE NOT IN COMPLETE AGREEMENT...BUT WE ARE FAVORING THE ECMWF WHICH DEVELOPS A BROAD LOW PRESSURE TROUGH OVER THE WESTERN STATES. THIS SCENARIO WILL BE DRY AND COOLER FOR SW CA WITH TEMPS CLOSE TO...OR SLIGHTLY BELOW THE SEASONAL AVERAGES. && .AVIATION... 010300Z...MARINE INVERSION BASE IS AVERAGING AROUND 800 FEET MSL. MID/HIGH CLOUDS MOVING OVER THE AREA...GENERALLY ABOVE FL120...WILL DECREASE SOMEWHAT OVERNIGHT. AREAS OF STRATUS/FOG WILL OCCUR MOSTLY WITHIN 5-10 MILES OF THE COAST BETWEEN 05Z AND 17Z...WITH LOCAL FOG NEAR THE BEACHES TUE AFTERNOON. CIGS WILL BE 800 FT MSL OR LESS WITH LOCAL VIS BELOW 1 MILE. THERE IS A GREATER THAN 50 PERCENT CHANCE THAT KSAN WILL HAVE VIS/CIGS BELOW CRITICAL MINIMUMS OF 1 MILE/400 FEET AT SOME POINT OVERNIGHT. CU/TCU WILL OCCUR OVER THE MTNS AND SOME ADJACENT AREAS TUE AFTERNOON...WITH BASES ABOVE FL080. ISOLATED TSTORMS WILL ALSO BE POSSIBLE WITH TOPS TO FL400. && .SGX WATCHES/WARNINGS/ADVISORIES... SPECIAL WEATHER STATEMENT FOR THE HOT WEATHER...SEE LAXSPSSGX. && PUBLIC...JAD AVIATION...MAXWELL
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE SAN DIEGO CA 400 PM PDT MON AUG 31 2009 CAZ042-043-048-050-055>058-060>062-PZZ750-775-011100- ORANGE COUNTY COASTAL AREAS-SAN DIEGO COUNTY COASTAL AREAS- SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE- SAN DIEGO COUNTY VALLEYS-SAN BERNARDINO COUNTY MOUNTAINS- RIVERSIDE COUNTY MOUNTAINS-SANTA ANA MOUNTAINS AND FOOTHILLS- SAN DIEGO COUNTY MOUNTAINS-APPLE AND LUCERNE VALLEYS- COACHELLA VALLEY-SAN DIEGO COUNTY DESERTS- COASTAL WATERS FROM SAN MATEO POINT TO THE MEXICAN BORDER AND OUT 30 NM- WATERS FROM SAN MATEO POINT TO THE MEXICAN BORDER EXTENDING 30 TO 60 NM OUT INCLUDING SAN CLEMENTE ISLAND- 400 PM PDT MON AUG 31 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR EXTREME SOUTHWESTERN CALIFORNIA. .DAY ONE...TONIGHT PATCHY DENSE FOG POSSIBLE IN THE COASTAL AREAS LATE TONIGHT. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY CONTINUED HOT DAYS INLAND THROUGH THURSDAY. SLIGHT CHANCE OF THUNDERSTORMS OVER THE MOUNTAINS AND DESERTS TUESDAY AND WEDNESDAY AFTERNOON AND EVENING. THE FLASH FLOOD POTENTIAL INDEX IS LOW...THE RISK OF ANY FLASH FLOODING IN MINIMAL. .SPOTTER INFORMATION STATEMENT...SKYWARN SPOTTER ACTIVATION IS NOT REQUESTED FOR THIS AREA...HOWEVER WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS. JAD
The national radar mosaic for the moment the first event began.
11 drought. Local standard time, as filed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2009Every state in 2009This day in weather historyWarnings in California, September 2009
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: 197815, 197816, 197817, 197818, 197819, 197820, 197821, 197822, 197823, 197824, 197825.