Winter Storm Timeline: When to Expect Rain and Snow in Southern California

The Friday morning drive will likely be wet.

“You don’t want to be on the road (Friday),” said De Leon.

At 4 a.m., showers will develop in Ventura County and parts of LA County. Rain will spread across the region during the middle of the day, including pockets of heavy rain.

“The rain is getting heavier Friday evening through Saturday morning,” said De Leon.

Saturday: Rain, Snow Through the Morning

Two to 5 feet of snow are expected above 5,000 feet by Saturday as the storm continues to hammer the region. Some areas could get as much as 7 feet.

Snow accumulations of 6 to 12 inches are possible by Saturday night at elevations as low as 2,000 feet.

Heavy rain will fall overnight in widespread parts of Southern California. By 10 a.m., snow and rain will begin to diminish with showers lingering into Sunday.

Rain and Snow Estimates

Rainfall estimates range from 2 to 5 inches for most areas and 5 to 7 inches in foothill communities.

Snowfall estimates include 2 to 5 feet, and possibly up to 7 feet, above 5,000 feet. Elevations between 3,500 and 4,500 feet will see 6 to 18 inches of snow.  

Another storm is on track to arrive Tuesday into Wednesday.

A blizzard warning was issued for LA and Ventura county mountains. Stephanie Olmo reports for the NBC4 News at 4 p.m. on Wednesday Feb. 23, 2023.

What’s a Blizzard Warning?

A blizzard warning generally indicates winter weather conditions that include snow, blowing snow, reduced visibility, strong sustained winds. It is a more severe weather warning that a winter storm warning.

Here’s how the National Weather Service defines a blizzard warning.

The following conditions are occurring or expected within the next 12 to 18 hours.

1. Snow and/or blowing snow reducing visibility to 1/4 mile or less for 3 hours or longer
   and
2. Sustained winds of 35 mph or greater or frequent gusts to 35 mph or greater.

Note that there is no temperature requirement that must be met for blizzard conditions.

SoCal Weather Photos: Scenes From the Late-February Winter Storm

A less severe winter storm warning is issued when a combination of hazardous winter weather is occurring or imminent.

Significant and hazardous winter weather is defined by the National Weather Service as a combination of the following.

1. Five inches or more of snow/sleet within a 12-hour period or 7 inches or more of snow/sleet within a 24-hour period
   and/or
2. Enough ice accumulation to cause damage to trees or powerlines
   and/or
3. A life threatening or damaging combination of snow and/or ice accumulation with wind.

California Drought Update

The most severe drought conditions that plagued California at the start of the water year in October were wiped out by January’s storms, which also were fueled by atmospheric rivers.

In the most recent U.S. Drought Monitor report released Thursday, 33 percent of California was in severe drought, the weekly Monitor’s third most severe category. At the start of the water year, 94 percent of the state was in severe drought.

Eighty-five percent of the state remains in moderate drought, the report’s least severe category. That figure was at 99.76 percent at the start of the water year.

California has spent most of the last 15 years in drought conditions. The current three-year dry spell included one of the driest late winters on record. 

The state’s normal wet season runs from late fall to the end of winter, but dismal precipitation left about 95 percent of California in severe drought at the start of spring. By September, nearly all of California was in drought.

Much of California’s water comes from melting snow in the Sierra Nevada Mountains. In an ideal scenario, storms blanket the mountains with snow during winter, building up the natural reservoir. That snow then melts in late spring and early summer, replenishing the state’s water system. Snowpack was far below normal in Spring 2022, but rebounded during January’s storms.