Rain is expected to hit California, Arizona and Nevada on Wednesday and Christmas, along with no rain but unseasonal, record-breaking heat in Colorado.

California

Rain is expected throughout California, with the brunt of it starting at midnight Tuesday and continuing through Friday, according to the National Weather Service. In Southern California, the agency predicted between 3 to 6 inches of rain in the coastal and valley areas and 5 to 11 inches in the foothills and mountains.

"A powerful winter storm will bring heavy rain and strong winds to the area through Christmas Day," the National Weather Service said. "Significant flooding issues are likely along with the potential for strong thunderstorms."

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There's a moderate risk of debris flows in the burn areas from January's wildfires, according to the Los Angeles County Public Works Department.

“Be aware: It will take less and less rain for there to be more and more impact as the week progresses,” the National Weather Service said on its website. The agency’s office in Oxnard, which serves Los Angeles, Ventura, Santa Barbara and San Luis Obispo counties, couldn’t be reached for further comment.

A flash flood watch went into effect at 4 p.m. Tuesday and was scheduled to last through 10 p.m. Christmas, according to Los Angeles Mayor Karen Bass’ office.

“An evacuation warning is now in effect through 11 p.m. on Thursday for the Palisades, Sunset and Hurst burn scar areas,” Bass’ office said in an email.

“All Angelenos – especially those in burn scar areas – are encouraged to stay informed and use caution while driving on the roads, which could see flooding,” the office said.

On its website, Los Angeles County urged caution in scar areas that are susceptible to mud and debris flows.

The Los Angeles Police Department and the Los Angeles County Sheriff’s Department knocked on doors at vulnerable residents’ homes to advise them of evacuation warnings.

While the heaviest of the rain will end on Christmas, the weather service said there would be a "cool and showery pattern" on Friday and Saturday.

Nevada

Rain is expected to hit Las Vegas Wednesday, according to the National Weather Service. The forecast calls for rain mainly through Friday. The weather service said a 24-hour flood watch would start at 4 a.m. Wednesday.

The chance of rain is put at 100 percent up north in Carson City on Wednesday, with snow expected at the 6,800-foot altitude. The snow level will fall to 5,800 feet by Thursday, the weather service said.

Between a quarter and a half of an inch of rain is possible in Carson City on Christmas Day, the weather service said.

Arizona

Showers are expected before 1 a.m. Wednesday in Phoenix, according to the National Weather Service. There’s a 30 percent chance of rain Wednesday in the Arizona capital, but that increases to 70 percent by Wednesday night. Showers are likely before 11 a.m. on Christmas, the weather service said.

The chance of showers will fall to 20 percent by Friday morning.

Elsewhere in Southern Arizona, Tucson is expected to have a 50 percent chance of showers, mainly after 11 p.m. Tuesday, followed by 40 percent on Wednesday and 50 percent on Christmas.

Rain is more likely up north in Flagstaff, the weather service said, with the chance of precipitation at 80 percent on Wednesday and 90 percent on Wednesday night and Christmas Day. A chance of rain and snow showers was forecast for Christmas night and Friday. There's a 50 percent chance of snow showers on Saturday.

Colorado

Colorado is known for its snow-capped Rockies, skiing and usually much cooler December temperatures than Southern California. But this week, it’s known for something else: unseasonal, record-breaking heat.

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A high near 70, along with mostly sunny skies, was expected Tuesday in Denver, according to the National Weather Service. The forecast for the area is partly sunny on Wednesday, with a high near 67, and mostly sunny on Christmas Day with a high near 70.

A high near 71 was predicted for Pueblo on Tuesday, with a high near 70 on Wednesday. Tuesday is sunny, and Wednesday is expectedly to be partly sunny. Christmas Day will be mostly sunny, the National Weather Service said.

Conditions will continue to vary from mostly cloudy to mostly sunny in Denver and Pueblo, but temperatures will fall to a high near the mid-60s and a more seasonal mid-50s on Saturday.

Boulder on Monday saw a record-breaking high of 72. The previous record for Dec. 22 was 70, set in 1955.

Statewide, records highs were set on Dec. 11, according to media reports.

Typically, Colorado sees highs in the 40s in December.