The upper-level ridge centered over the Four Corners region built westward into California on August 6th, heralding the start of a near-record string of days with above-normal temperatures. After two days with highs of 99, Fresno again had a triple-digit high, the first of 19 consecutive days when the high was 100 degrees or higher. An Excessive Heat Watch was issued on the 7th for elevations below 4000 feet from August 10th through the 12th for near-record high temperatures.
Monsoonal moisture wrapping around the ridge moved into California, triggering thunderstorms over the Southern Sierra Nevada and the Kern County desert on August 9th. One afternoon thunderstorm that moved into Kern County between Boron and Edwards AFB had gusts to 45 mph.  Other thunderstorms just east of Kern County, or over western San Bernardino County, produced gusts to 45 mph as they collapsed during the evening hours. These gusts also moved into southeastern Kern County. A spotter in Rosamond reported a wind-driven dust cloud that moved through Rosamond.
The 9th also saw the Excessive Heat Watch upgraded to a Warning as computer model runs continued to forecast near-record heat for August 10th-12th. With well above-normal temperatures and abundant monsoonal moisture, convection again fired up over the mountains and desert on the 10th. During this day, lightning sparked another large wildfire in the Kern County mountains, called the Jawbone Complex (about 15 miles northeast of Tehachapi).
As expected, temperature records began falling as the strong upper-level ridge remained in place over the southwestern United States. The Kern County desert initially recorded the warmest temperatures; however, enough monsoonal moisture returned to allow blow-off from the isolated thunderstorms to form a cloud layer over these areas by the 11th so that temperatures moderated. In contrast, temperatures continued to warm over the San Joaquin Valley, where Fresno and Bakersfield reached 110 degrees on the 13th.
On August 12th, a thunderstorm developed near Mojave that produced a 57 mph wind gust, prompting a severe thunderstorm warning to be issued. Thunderstorms lasted through the afternoon and early evening hours during this day throughout the desert areas in Kern County.
By August 13th, an upper-level low was located off the Pacific coast of Baja California. The combination of the ridge over the Southwest and the low off the coast kept a southeasterly flow over California that continued to bring monsoonal moisture into the state from the south. This moisture produced mid-level clouds that persisted over parts of the San Joaquin Valley, even during the night-time hours and kept overnight lows at record or near-record high values.
Thunderstorms developed again by midday on August 13th, with lightning strikes occurring from the eastern Tehachapi Mountains north to Yosemite National Park. Some of these strikes triggered wildfires in the Southern Sierra Nevada and near Tehachapi, including the multi-fire Tehachapi Complex, and outflow winds gusted to around 50 mph in Ridgecrest. At the lower elevations, well-above-normal temperatures continued, prompting a one day extension of the Excessive Heat Warning.
August 14th saw more thunderstorms over the mountains and desert as monsoonal moisture continued to stream into the hot airmass over the central California interior. One thunderstorm over southeastern Kern County reached severe levels, as outflow winds reached 67 mph at Edwards Air Force Base.  Also, clouds from this monsoonal moisture kept overnight lows at record warm levels. Both Bakersfield and Fresno set high minimum temperature records. Bakersfield never got below 83 degrees, and Fresno was only a degree cooler.
Local media reported a window washer in Bakersfield was hospitalized and suffered heat illness during the August 14th heat wave.

Heat in W CENTRAL S.J. VALLEY, CALIFORNIA
From 10-AUG-12 11:00:00 to 12-AUG-12 22:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Heat in E CENTRAL S.J. VALLEY, CALIFORNIA
From 10-AUG-12 11:00:00 to 12-AUG-12 22:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Heat in SW S.J. VALLEY, CALIFORNIA
From 10-AUG-12 11:00:00 to 12-AUG-12 22:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Heat in SE S.J. VALLEY, CALIFORNIA
From 10-AUG-12 11:00:00 to 12-AUG-12 22:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Heat in S SIERRA FOOTHILLS, CALIFORNIA
From 10-AUG-12 11:00:00 to 12-AUG-12 22:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Heat in TULARE CTY FOOTHILLS, CALIFORNIA
From 10-AUG-12 11:00:00 to 12-AUG-12 22:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Heat in KERN CTY MTNS, CALIFORNIA
From 10-AUG-12 11:00:00 to 12-AUG-12 22:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Dust Storm in SE KERN CTY DESERT, CALIFORNIA
From 09-AUG-12 16:00:00 to 09-AUG-12 16:10:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in KERN, CALIFORNIA
From 12-AUG-12 16:30:00 to 12-AUG-12 16:40:00 (PST-8)
Location: MOJAVE ARPT
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

A thunderstorm created severe outflow winds in Mojave.

Heat in W CENTRAL S.J. VALLEY, CALIFORNIA
From 13-AUG-12 02:50:00 to 13-AUG-12 22:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Heat in E CENTRAL S.J. VALLEY, CALIFORNIA
From 13-AUG-12 02:50:00 to 13-AUG-12 22:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Heat in SW S.J. VALLEY, CALIFORNIA
From 13-AUG-12 02:50:00 to 13-AUG-12 22:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Heat in SE S.J. VALLEY, CALIFORNIA
From 13-AUG-12 02:50:00 to 13-AUG-12 22:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Thunderstorm Wind in KERN, CALIFORNIA
From 14-AUG-12 14:50:00 to 14-AUG-12 15:15:00 (PST-8)
Location: EDWARDS
Magnitude: 58.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Other Federal Agency

Edwards Runway wind sensors measured wind gusts up to 67 mph from a severe thunderstorm downburst and outflow. Blowing dust also reported at Edwards AFB.