In California, Governor Arnold Schwarzenegger declared a state of emergency in seven counties in the San Francisco region as heavy rains triggered floods.
Meanwhile, runaway fires that killed at least four people have continued to rage across the southern central US states of Texas and Oklahoma, forcing residents to flee.
Traci Weaver, a spokeswoman for the Texas Forest Service, said at least 80 homes were lost in Texas, while three communities and two small towns had to be evacuated.
However she added that some headway has been made in taming the blazes, which were sparked by a drought, warmer than usual temperatures, and high winds.
"We still have five active fires out of 18 yesterday," Ms Weaver said.
"Unfortunately, the winds have shifted towards north-northwest which isn't good news. The temperatures are cooler today, but the winds are threatening."
Homes, farmland destroyed
Ms Weaver said one of the main fires has already destroyed 13,800 hectares, as well as 35 homes.
Another blaze, burning on a 27-kilometre front, has destroyed 40 homes.
Emergency preparedness officials in the parched state of Oklahoma said fires have burned in two dozen counties in the last five days and the state is bracing for "extremely dangerous" wildfire conditions.
Oklahoma Governor Brad Henry said he has asked US President George W Bush to declare an emergency in the state and commit federal resources to battling the fires, which have scorched huge swaths of the largely rural state since Tuesday.
"Most of these fires are caused by human carelessness. We are asking people to use extreme caution," Governor Henry told CNN television.
"We are literally at the mercy of the weather. We have no appreciable precipitation forecast."
In the state of New Mexico, a spokesman with the state's forestry department said that even extinguished fires are proving challenging for firefighters.
"We've got five major fires, all of them are laid down at the moment," spokesman Dan Ware said.
"Our firefighters are trying to keep the fires from reigniting."
In the town of Tatum, about 700 residents were evacuated but were allowed to return to their homes shortly afterwards.
In the town of Hobbs, where close to 20 structures were destroyed by fire, between 300 and 500 people had been evacuated, officials said.
The mayor of Oklahoma City, Mick Cornett, said on Monday that there is no relief in sight.
"I'm concerned that the worst may be yet to come. There's no rain in the forecast," said Mayor Cornett, who said there has been no significant rainfall in the area since late October.
Heavy rain
Meanwhile, heavy rains continue to inundate California's wine country.
Around 4,000 people in northern California's Napa, Sonoma and Marin counties were forced to flee their homes to escape the regions' overflowing rivers, officials said.
Torrential rains which deluged San Francisco over the New Year's holiday weekend have migrated southward, drenching usually sunny southern California.
The US National Weather Service (NWS) issued a flood warning for the central and southern San Joaquin Valley through late Monday.
Forecasters anticipated another inch (2.5 centimetres) of rainfall on top of several inches that have already fallen over the past several days, further swelling waterways, especially in low lying areas.
The western flooding stood in stark contrast to conditions in parched southern plains states, where a drought was expected to persist.
Across central and eastern Texas, central and eastern Oklahoma and western Arkansas the lack of rainfall has been described as "severe" to "exceptional".
Parched grasses are fueling the flames. Weather officials said that by year's end precipitation was 56 centimeters below average in Denton, Texas, and 36 centimeters short in Tulsa, Oklahoma.
"It's extremely dry and about every other day it's extremely windy. You put those in a combination and it's a dangerous combination. I'm concerned it may get worse before it gets better," Mayor Cornett said.
The NWS has predicted more warm weather with high wind gusts, which are likely to fan any flames.