A firefighter runs while trying to save a home as a wildfire tears through Lakeport, California. Credit:AP Australia, as well as a number of other countries, has offered ongoing support to US firefighting authorities; the Australian deployment is a response to a specific request from the US based on the range of skills offered. It includes firefighters also from Victoria, Queensland and South Australia. The request was made to Australia by the National Multi-Agency Coordination Group in the US, which is co-ordinating the efforts of several emergency response agencies, including the Department of Forestry and Fire Protection (CalFire). Australia's expertise was sought by US authorities because of our familiarity with bushfires; in the US media such fires are referred to as "wildfires".

Australian fire specialists prepare to board a fight to California on Friday. Credit:AAP The current US fire season has been exacerbated by excessively dry and hot weather conditions, resulting in intense fire fronts and dangerously low percentages of fire containment. More than 40,000 were under evacuation orders on Friday but - extraordinarily - just eight people have been killed. Some 24,000 remained displaced as of Friday. A firefighter rushes to save a home as the River Fire tears through Lakeport, California, on Tuesday. Credit:AP Among the dead are three firefighting personnel and a bulldozer operator working at a fire front; authorities say a number more are still missing.

The two major fire fronts are the Carr fire, which has, as of Friday US time, burn through approximately 50,926 hectares and is approximately 35 per cent contained, and the Ranch fire, which now covers around 30,306 hectares are is approximately 33 per cent contained. In a marked shift from last weekend, when many of the fires were out of control and as little as five per cent contained, crews battling the key fire fronts are now reporting containment as high as 35 per cent, and in some cases, 50 per cent containment. More than 100 large fires were burning across 14 states and almost 582,000 hectares of ground has been lost, according to the National Interagency Fire Centre. In addition to California, there are currently major fires burning in Alaska, Arizona, Colorado, Florida, Idaho, Montana, Nevada, New Mexico, Oklahoma, Oregon, Utah, Washington and Wyoming. A bulldozer operator builds containment lines while battling the River fire in Lakeport. Not all firefighters carry a hose or a shovel. The adrenaline junkies who steer heavy bulldozers across steep ridges face many dangers, from the flames themselves but also from unsteady dirt and rocky terrain. Credit:AP

Of the firefighting force of 12,000 on the ground, around 3000 are prison inmates deployed as part of the Conservation Camps program which is jointly managed by CalFire and the California Department of Corrections and Rehabilitation (CDCR). The inmate firefighters are paid $US2 per day plus $US1 per hour; that compares with the regular pay of CalFire firefighters which is $US10.50 or more per hour. Only approximately 3800 state prison inmates in California meet the minimum-custody and low-risk requirements for the firefighting assignment. (Sex offenders, past escapees and, understandably, arsonists are ineligible for the program.) Though the prominence of inmate firefighters is relatively low in media terms, their presence on the front lines is not new; CalFire says inmate firefighters have been deployed in California since World War II when much of the state's manpower was focused on the war effort. Inmate firefighters usually make up roughly one third of the state’s wildfire-fighting crews - that is closer to about a quarter at present as the total deployment includes crews from out of state and overseas - and, in addition to fighting fires, also work on park maintenance, reforestation, and fire and flood protection.

A helicopter carries water to drop on an advancing wildfire near Finley, California. Credit:AP The fires have been fuelled by an excessively hot California summer, with low rainfall, low humidity and high temperatures; the resulting extreme heat creates unusual and unpredictable weather conditions for firefighters. The worst of that was the "rotation updraft" reported earlier this week at the Carr fire front in which a vortex of fire and smoke similar to a tornado is formed, pulling up and spraying out burning embers and other fire debris. CalFire's public information officer Jonathan Cox said the blazes were larger in scale and burning at speeds previously unseen. "What we're seeing in California right now is more destructive, larger fires burning at rates that we have historically never seen," Mr Cox said.

The Carr fire began last Monday after a vehicle suffered mechanical failure, CalFire said; fuelled by high temperatures, low humidity and wind, the fire doubled in size over the weekend. California Governor Jerry Brown said the wildfire season was the "new normal" for the state. To illustrate his point, Brown told US media the state had already spent more than a quarter of the budget allocated for resources across the entire annual fire season in the month of July alone. "We're going to have more fire, more destructive fire, [and] more billions that will have to be spent on it," Brown said. "All that is the new normal that we will have to face." Weather agencies report that the current burst of fires came off the back of record-setting July temperatures; in northern California, for example, July temperatures were as much as 10 degree Fahrenheit higher than normal.