[7] For the first time since 1977, the US military helped with ground-based firefighting, when Governor Arnold Schwarzenegger dispatched 400 California National Guard troops, including Chief Medical Officer Susan Pangelinan, to manage fire lines.

International aid from Greece, Cyprus, Chile, Argentina, Brazil, Australia, Canada, Mexico, and New Zealand helped fight the fires.

Total resources included 467 hand crews, 1,503 engines, 423 water tenders, 291 bulldozers, 142 helicopters, 400 soldiers and numerous air tankers.

[20][21] On July 25, a blaze sparked by target shooting broke out in Mariposa County, in the Sierra Nevada foothills of central California.

[citation needed] The fires broke out after three years of below-normal rainfall dehydrated much of California's forests and woodlands, making them prone to wildfires.

[11][30] As vegetation turned into bone-dry tinder in early June, Governor Arnold Schwarzenegger declared a statewide drought for the first time in 17 years.

[32][33] The number of wildfires skyrocketed in the days after the thunderstorms and high daily daytime temperatures of over 120 °F (49 °C) dramatically increased the various fires' growth.

[citation needed] A heat wave commenced on July 7, with temperatures in inland locations, such as the Central Valley soaring above 115 °F (46 °C).

[35][36] John Juskie, a National Weather Service science officer, was quoted in June 2008 in the Los Angeles Times stating "in historic terms, we're at record dry levels.

[37] A record lack of rainfall, severely dry vegetation and uncharacteristically windy weather combined to create tinderbox conditions across Northern California.

[38] These smoky and hazy conditions prompted health officials to issue air quality advisories and warnings, as particulate matter reached unhealthy levels in the North Bay on June 25.

The bad air quality also forced the cancellation of the 100-mile (161 km) Western States Endurance Run, the first in the race's 31-year history.

[43] By June 30, residents in the Sacramento Valley saw blue skies and good air quality, as a result of onshore winds and the Delta breezes.

A paper in the American Journal of Respiratory Cell and Molecular Biology studied a group of adolescent rhesus macaque monkeys that were exposed during infancy to smoke from northern California wildfires in 2008.

Adolescent monkeys exposed to wildfire smoke as infants were also found to have a lessened PBMCs responses to TLR Ligands.

[48] The findings were consistent with many other human group studies and suggest that children who underwent the same experience as the monkeys in the study have a high chance of exhibiting similar health problems but, that because normal development of rhesus monkeys is accelerated compared to human children the relative impact of this amount of wildfire smoke exposure might differ.

"[50] California Governor Arnold Schwarzenegger declared a state of emergency in Santa Barbara, Los Angeles, and Orange Counties.