Precipitation Fires Up Across the Southwestern U.S. Early This Week

A surge of moisture is going to bring valley rain and mountain snow to a large part of the Southwest to start the week. The system is part of the event that has been providing relief to firefighters in Southern California. Here is a look at this evolving storm and where it is headed next.

Rain Delivers Relief to Parched Landscape in Southern California

Relief finally arrived in Southern California over the weekend, giving a boost to crews working to gain the upper hand on the ongoing wildfire situation. An area of upper-level energy is moving to the south through the region, ushering in much-needed moisture.

The rain began to fall on Saturday afternoon across the Los Angeles basin and the nearby valleys. The rain event was the first significant moisture for some parts of Southern California since April of 2024. The moisture train increased throughout the day Sunday with total rainfall amounts of up to an inch for much of Los Angeles and down into San Diego expected by the time the system dissipates.

The new week will bring a renewed risk of rain and potentially even thunderstorms or small hail for some parts of the Central Valley and into the Los Angeles basin thanks to an onshore flow pulling the moisture from the Pacific Ocean farther inland.

Monday's forecast is calling for the soggy weather to continue to linger, targeting parts of interstates 5, 8, 10, and 15 with moisture. The upslope regions of the San Gabriel, San Bernardino, and Santa Rosa mountains will see the greatest amount of rain with 1 to 2 inches of rain in the forecast by the time drier weather arrives.

Moving farther inland, cities such as Bakersfield should prepare for rainfall between 0.25 and 0.50 of an inch. Monday's highs will top out at about 57 degrees in Bakersfield despite the emergence of some sunshine after the rain.

System Moves Into the Southwest

The weather maker will move into the Desert Southwest after soaking Southern California. Forecasters predict that this could be the biggest storm of the season for some parts of the southwestern U.S. thus far. In addition to rain in the lower elevations, substantial amounts of snow will impact the higher terrains.

The event will bring an end to the ongoing streak of dry days. For instance, Las Vegas has not seen any measurable rain since July 13, good enough for the second-longest dry spell in recorded history for the city. As of Sunday, it had been 196 days of no rain for Sin City. The record is 240 straight dry days, dating back to 2020.

While it will not be a washout on Monday in Las Vegas, the city will see morning rain showers before the sun makes an appearance in the latter part of the day. It will be unseasonably chilly with a high of about 55 degrees and lows that slide into the mid 30s.

Rain showers will also be in the cards for Phoenix. The Valley of the Sun is forecast to see cloudy conditions on Monday with a good chance of light rain showers. The mercury will top out at about 61 degrees with lows that fall to about 43 degrees overnight. The brief shot of rain will not last long for the metro area with clearing conditions and mild temperatures on tap for the rest of the week.

Snow for the Mountainous Areas of the Southwest

This same storm system will bring in air that is cold enough to support the development of snow in the higher terrains. After flakes flew across the mountains of Southern California to close out the weekend, the line of snow will move into the mountainous regions of Arizona and New Mexico on Monday and Tuesday.

Motorists heading out on Interstate 40 in this zone will want to monitor road conditions as things could become slippery quickly. Some portions of Interstate 17 and Interstate 25 could also see dicy road conditions as the storm moves to the east.

Flagstaff, Arizona is expecting about an inch of snow on Monday during the daytime hours Monday, approximately 1 to 3 inches of snow on Tuesday, and the chance of more flurries on Wednesday. Highs will hover in the mid 30s during this time period with lows dipping into the mid teens.

The storm will move over the mountains in the Southwest by the middle of the week, bringing up a renewed surge of moisture and energy as it tracks into the southern Plains. This will translate to a mix of snow, rain, and ice for different areas of New Mexico, Texas, Colorado, Oklahoma, and Kansas.

For instance, the snow will hit places such as Taos, New Mexico by late Tuesday with an inch in the forecast overnight. Wednesday's forecast in Taos is calling for 1 to 3 inches of snow during the day and another 1 to 3 inches expected after the sun goes down. The mountain resort town will see another inch of snow on Thursday with drier conditions heading into the weekend. Highs will bounce around in the mid 30s to about 40 degrees on Wednesday and Thursday before inching back into the mid 40s by the end of the week.

Warmer temperatures in Lubbock, Texas will mean that the moisture will fall as rain on Wednesday. The city in the panhandle region is expecting a high in the low to mid 50s for the first few days of the week with lows tumbling to about the 40-degree mark overnight.

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