Parts of Southern California were under a flash flood watch Wednesday as areas of the southwest saw the first significant rainfall of a delayed wet season that fueled wildfires and forced intermittent power cutoffs to millions of residents.

The storm system brought heavy rain to portions of Arizona, and Phoenix could get 2 inches of rain before the rain ends there on Thursday. Prior to this storm, Sky Harbor International Airport had officially recorded only 3.68 inches for the entire year.

Los Angeles has only had one day of traceable rain in almost two months. But an upper level, low pressure system approaching the California coast was bringing “significantly cooler and showery conditions” to the Los Angeles and San Diego areas, the National Weather Service said.

Power outages, again? 750,000 people in Northern California could be left in the dark this week, PG&E warns

There will be some mountain snow and a slight chance for thunderstorms, with showers lingering into Thursday, forecasters said.

“The first rain of the season is about to arrive, but at the moment it is nothing to write home about,” the weather service said in a statement early Wednesday. “There is not much rain so far.”

Still, the weather service said the “best dynamics” for rain will be focused from Los Angeles County to Orange County with much less shower activity across Ventura and other counties northwest of the city.

Rain has been so rare that the Los Angeles Times included a link on “How to drive in the rain” on its website.

To the east, the rains were in full force Wednesday. Caltrans was tweeting warnings of flooding on multiple roads. The National Weather Service issued a flash flood warning for San Bernardino and Riverside counties, saying localized, heavy rainfall could drive mudslides through steep terrain in recently burned areas. 

Still, much of the state remained in dire need of precipitation. More than 81% of the state is considered “abnormally” dry, including a small percentage in the first stages of drought, according to the most recent U.S. Drought Monitor. 

Pacific Gas & Electric was tentatively scheduled to preemptively cut power to hundreds of thousands of residents of more than a dozen counties in Northern and Central California.

“The decision was based on weather forecasts indicating the potential for high winds and dry conditions leading to increased fire risk,” PG&E said in a statement.

Contributing: Doyle Rice, USA TODAY; Ayano Nagaishi and Chris Coppola, Arizona Republic