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2004: Early morning thunderstorms swept across the Southern California region bringing locally heavy rain and copious lightning.
Lightning strikes started numerous small fires, including more than a dozen in the San Gorgonio Wilderness Area in the eastern San Bernardino Mountains.
2004: Monsoon thunderstorms produced 0.71" of rain in 30 minutes in Phelan, 0.63" in eight minutes at Volcan Mountain (north of Julian), 0.66" in 11 minutes in San Felipe Valley (south of Borrego Springs).On this day flash floods hit Wildomar, Sage, and La Quinta.
Hwy. 78 near Yaqui Pass was closed because of flash flooding.
2004: An evening thunderstorm produced 60-70 mph wind gusts at Edwards AFB.
1998: Strong thunderstorms developed each day in the valleys and the deserts starting on 8.12 and ending on 8.14.
Flash flooding and very strong winds resulted in Apple Valley.
A thunderstorm in Hemet produced a downburst with winds to 70 mph and 0.75" hail that damaged buildings, trees, and power lines.
Golf ball size hail fell at Cajon Pass.
1.6" of rain fell in 30 minutes at Boulevard.
1996: Three Rivers has a high temperature of 114° F at the Edison Power House #1, highest ever at this station.
1992: A massive outbreak of tropical moisture in the form of a Mesoscale Convective System created severe thunderstorms which developed over the mountains and deserts of Southern California bringing historic August rainfall.
Palomar Mountain reported an event total rainfall of 6.47" in a mere 90 minutes breaking its monthly record for single day rainfall by nearly 4".
Mount Laguna also recieved close to 4" of rain in just 2 hours.
1982: A total of 4.5" of rain fell in Searchlight, NV, making this the wettest calendar day ever and the only time over 4" of rain has fallen on one day.
1977: Hurricane Doreen paralleled the west coast of Baja before dissipating west of San Diego. Severe flooding occurs in Yuma County, and around Bullhead City.
Rainfall in Yuma totals 2.96".
Severe flooding also occurred in California's Imperial Valley.
1972: Tropical Storm Diane sent moisture into the region which produced a thunderstorm in the Afton area, about 40 miles northeast of Barstow.
Visibility was reduced to near zero.
Flash floods covered Interstate 15 and closed it for half a day.
Other roads and railroads were washed out.
1971: During the time from 8.11 to this day it was 100° F in Palomar Mountain.
This highest temperature on record also occurred on 5 other days.
1971: Monsoonal thunderstorms caused problems in San Bernardino County, where a flash flood washed out a bridge along Interstate 40 and severe winds downed trees and utility lines, and overturned several mobile homes.
1948: Oakland had a high temperature of 104° F.
1933: Hanford reached a high of 115° F, establishing an all-time record high for the month of August.
1933: A Southern California heat wave began on 8.10 and ended on this day in the valleys; temperatures topped 110° F for several consecutive days.
1933: The high temperature at Reno, NV was reported at 103° F.
1868: Two earthquakes near M8.5 off Chile produced a 2.64 foot wave height in San Diego.
Source: NWS San Francisco/Monterey, Hanford, Reno, Las Vegas, Phoenix, & San Diego