MONTHLY WEATHER SUMMARY
By Bill Mork
California Department of Water Resources
October 2004

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October 2004 was cool and unseasonably wet with a mean upper level trough of low pressure near the West Coast and an active low latitude storm track which produced record October rainfall totals in much of Southern California. Preliminary data show the statewide average temperature in October to be 58.3 degrees, 2.4 degrees below normal, and more like November at many locations on the South Coast which averaged 3.6 degrees below normal.  Departures from normal average temperatures were as much as minus 5.6 degrees at Culver City, minus 4.7 degrees at Alpine and Porterville, and minus 4.4 degrees in downtown Los Angeles.  Rain at San Diego on the 17 th (0.09 inches) ended its record consecutive-day rainless streak at 182 days, April 18 to October 16, with records going back to 1850. 

There were three major storms which brought precipitation to most of the State, with heaviest totals in Southern California , centered on October 16-18, 19-21, and 26-28.  There were record daily rainfall totals at many locations on all days included in these stormy periods.  The most extreme rainfall event in the Southland was on October 19-20 in Los Angeles County when Opids Camp received 4.95 inches in 3 hours, 12.79 inches in 24 hours, and 14.63 inches for the storm in a 48-hour period.  The 24-hour total of 12.79 inches rivals the greatest daily rainfall amount on record for October in California of 14.11 inches at Boulder Creek in Santa Cruz County , according to Jim Goodridge, 1992, "A Study of 1000-Year Storms in California ".  The Opids Camp 24-hour total seems to easily outgun the previous Southland October record of 7.58 inches at Encinitas in 1889.  The peak 24-hour rainfall total in San Bernardino County on October 19-20 was 10.83 inches at San Sevaine Spreading Ground.  One of the heaviest major city daily totals was 2.70 inches at San Diego Lindbergh Field on October 27, the fourth wettest day since 1850 in San Diego and the wettest day since 2.71 inches fell on February 6, 1937 .  These extremely heavy rains created urban and local flash flooding, but very accurate National Weather Service quantitative precipitation forecasts likely were mitigating factors in the minimal casualty and damage figures in Southern California .

The big story for October is the monthly rainfall totals which set records at many locations in Southern California .  The 4.98 inches at San Diego was the wettest October since records commenced in 1850 at that location.  The October total of 4.56 inches in downtown Los Angeles was second only to the 6.96 inches in October 1889.  October totals of 2.45 inches at Fresno and 1.54 inches at Bakersfield tied for the fourth wettest Octobers on record at both locations.  The October total of 3.09 inches at Sacramento was the fifth wettest October since records began in 1850 at that location.  The October total of 6.89 inches at Santa Ana won the award for multiples as that total was over 19 times the normal of 0.36 inches.

Other record October totals we know of include 10.50 inches at Lake Elsinore, 9.74 at Glendale 3N, 7.65 at Idyllwild, 7.62 at Lodgepole, 7.56 at Glendale, 7.45 at Big Bear Lake, 5.90 at Escondido, 5.57 at Burbank, 5.43 at San Luis Obispo, 5.34 at Long Beach, 5.33 at Morro Bay, 5.24 at UCLA, 5.23 at Ojai, 5.10 at Lompoc, 5.05 at Burbank Airport, 4.96 at Alpine, 4.74 at Santa Paula, 4.54 at Fullerton, 4.21 at Riverside Citrus, 4.07 at Culver City, 3.90 at Paso Robles, 3.78 at LAX, 3.43 at Santa Barbara, 3.38 at King City, 3.35 at Sandberg, 2.79 at Salinas, 2.44 at Hollister, and 2.32 inches at Santa Maria. 

The Central Sierra Snow Lab at Soda Springs (Donner Summit) caught 17 inches of snow on October 26 with 24 inches on the ground.  The total October snowfall of 48 inches was the snowiest October since records began in 1945; the previous October record was 36 inches of snow in 2000.  Two more feet of snow on October 26 at Squaw Valley , on top of 6 feet of snow in the previous week, triggered the earliest opening of the ski season on October 30.  The Sugar Bowl ski resort also had its earliest opening ever on October 30 after getting two feet of fresh snow on October 26.

On a drier note, there were two major Santa Ana events in Southern California in October 2004.  On October 11-12, an upper level low pressure area dropping southwest of Los Angeles produced strong offshore winds which pushed the temperature to 93 degrees at Chatsworth on October 12.  The other event was on October 31 with gusts to 53 mph at Cheeseboro.

Page last updated 11/09/04.