Periodic moderate to heavy rainfall is forecast across most of the Inland Empire will continue Saturday and Sunday as one storm system remains followed by another one going into next week.
"A Flood Watch will go into effect for all areas from early Saturday morning through Saturday evening as this storm system moves over the region," said the National Weather Service. "This is when most areas will see the heaviest rainfall, including a chance for thunderstorms."
A flood watch will be in effect from 4 a.m. through 10 p.m. Saturday including in the cities of Cathedral City, La Quinta, Coachella, Indio, Palm Desert and Palm Springs.
The NWS said that troughs of low pressure sweeping out of the Pacific Northwest will spin into the region, generating some downpours, the heaviest of which will be in and around higher terrain.
"While confidence remains low on exact rainfall amounts due to the uncertainty of the storm's exact path, be prepared for locally heavy rainfall and an increase threat for flooding, including near former burn areas in the mountains," the NWS said in a statement. "Since this precipitation will be coming from the southeast or the south, the coastal slopes of the mountains may receive locally four to five inches or more of rainfall from Friday night into Saturday. There is also a chance of some embedded thunderstorms within this system as instability will be elevated."
Snow levels were predicted to hold at roughly 8,000 feet for the weekend.
Winds were expected to increase as the frontal boundary on the leading edge of the troughs traverses the area, with the highest gusts -- up to 40 mph -- in mountains and passes, including the San Gorgonio Pass, according to forecasters.
No flood, wind or winter weather advisories are currently in effect, but that may change once the storm system settles across the region.
Another round of wet weather will follow on Monday and Tuesday, though that trough is expected to be weaker.
This would be the first major system of the autumn season, the prior one in mid-October produced only about a half-inch of rainfall in the Riverside metropolitan area, according to the Weather Service.
High temperatures in the Riverside area will top out in the low 60s Thursday to Saturday, with lows all week in the upper 40s to low 50s.
For the Coachella Valley, highs will be in the low 70s going through the weekend. Lows will generally range from the low to upper 50s.
In the Temecula Valley, daytime temps will be in the low 60s through Saturday, with lows in the mid to upper 40s, according to the NWS.
With a storm expected to roll through the Coachella Valley, Imperial Irrigation District officials said they will be prepared to respond to any possible service disruptions.