Rialto, CA 92376 Weather

Synopsis

A low pressure system moving southward off the California coast will bring general cooling through Thursday. It is also expected to produce showers and a slight chance of thunderstorms for late Wednesday through Thursday is it moves inland through California into Nevada. Warmer and drier for next weekend. Offshore flow on Saturday could produce gusty northeast to east winds in and below mountain passes and canyons as well as the Inland Empire corridor between the Cajon Pass and the Santa Ana Mountains. The offshore flow weakens for Sunday into early next week.

Discussion

FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES...

This afternoon...Skies are partly cloudy with only a few low clouds off the coast, some mid and high clouds streaming in from the southwest and cumulus clouds developing over the mountains. Isolated showers over the mtns this afternoon can't be ruled out but the chances are very low. Temperatures are generally a few degrees lower than at this time yesterday.

The low pressure system west of Point Conception continues to move south today before turning east tomorrow. It will move through SoCal on Thursday and Friday. It will bring further cooling, a deepening marine layer with more low clouds, and widespread precipitation. Showers could spread into coastal areas during the afternoon on Wednesday. Those showers are expected to spread farther inland for Wednesday night into Thursday with the greatest chances for thunderstorms for late Wednesday night into Thursday.

Between Wednesday and Thursday night, rainfall across Orange and southwestern San Bernardino Counties could range from around 1 inch near the coast to as much as 2 inches in the mountains. Rainfall for San Diego County will range from around 1 inch in North County to 0.50 to 0.75 near the border. High desert areas will receive around 0.50 inch of rainfall and the low deserts will receive 0.25 inch or less. Probabilities for 0.10 inch or more of rainfall from Wednesday morning through Thursday night exceed 90 percent for the coast, valleys, and mountains. Probabilities for 0.50 inch or more exceed 80 percent for the mountains as far south as the northern half of San Diego County. Probabilities for 1 inch or more range from 15 to 50 percent from the coast to the mountains for Orange and southwestern San Bernardino Counties. Probabilities for 2 inches or more exceed 10 percent for the mountains of southwestern San Bernardino County.

High temperatures on Thursday will range from around 5 degrees below average near the coast to 15 to 20 degrees below average for mountain elevations above 6000 feet. High temperatures on Thursday will be in the 60s to around 70 for the coast and valleys and in the 40s and 50s for the mountains.

Precip tapers off late Thu into Fri as the low pressure system moves eastward into AZ.

Marine

A storm system will move through the coastal waters late Wednesday through Thursday. Southerly winds Wednesday will shift to southwesterly Wednesday night, then westerly Thursday, with occasional wind gusts exceeding 20 knots. There is a 10-20% chance of TSRA Wednesday night through Thursday. No additional hazardous marine conditions are expected Thursday night through Sunday.

Beaches

Southerly swells will continue to bring surf of 3 to 5 feet with sets to 6 feet, highest at south and southwest-facing beaches through this evening (locally to 7 feet at Huntington Beach/The Wedge). This will bring hazardous swimming conditions for most. While surf and rip currents will be elevated, daily high tides will not be particularly high, and the threat of coastal flooding is minimal. See the Beach Hazards Statement for more details.