Sometimes referred to as “the Devil’s Breath”, the winds of about 160km/h have stoked the fires and hampered efforts to tackle the blazes from the air.
US President George W Bush said: “I wish we could control the wind, because one of the things that’s hampering our joint capability of fighting these fires is the strong westerly winds.”
The Santa Ana winds begin when masses of cold air form over high desert plateaus in Utah and Nevada.
Spinning off these high pressure systems, the winds grow warmer, drier and stronger as they are channelled south and west down through mountain canyons towards the ocean.
A regular feature of Californian autumn and early winter seasons, they usually blow air pollution out to sea, but this week’s winds have reached speeds of about 160km/h, with devastating effects.
Mike Davis, a historian from the University of California, Irvine, told National Public Radio the high speed winds on Sunday rushed into canyons producing “literally a blast furnace effect at the other end of the canyon”.
The wildfires swept across seven counties in southern California, a region which has been mired in a severe drought for more than a year.
The US National Weather Service said one monitoring point, just above the Point Mugu Air Station, measured winds of 178km/h.
A Category 2 hurricane has winds of between 150km/h and 175km/h.
Forecasters said the wind were to begin to weaken over night and will be followed by cooling sea breezes.
Homeland Security Secretary Michael Chertoff, who visited the area, said the shift could allow for a greater aerial assault and help firefighters beat back the most destructive blazes.
Fire lines would then be able to be formed more successfully.
Mr Chertoff said: “If the weather cooperates, maybe we can turn the tide.”
410,000 acres — area wildfires have burned across Southern California for a fourth day.
20 — fires reported since Sunday, from Santa Barbara to the Mexican border. 500,000-plus — people have been evacuated.
1,500 — homes have been lost in the region and a further 68,000 homes are threatened statewide.
5 — people dead, around 45 injured, including at least 21 firefighters.
7 — southern counties declared disaster areas.
70 — mph hot winds.
6,000 — firefighters battling flames.
$1bn — in insurance to be claimed.
12,000 — evacuees spent the night at Qualcomm Stadium.
90— aircraft tackling fires.