textproduct: San Joaquin Valley

UPDATE

Updated air quality section.

KEY MESSAGES

1. System approaches the region this Wednesday bringing valley rain, mountain snow, and increased gusts in the desert areas.

2. Stable conditions beforehand with temperatures above season averages.

DISCUSSION

High pressure remains centered over the southwestern US this morning, including southern and central California. However, today will be the last day with this system over our area, with a more active pattern in store for the upcoming week. For Sunday, expect conditions similar to the end of last week, with afternoon temperatures in the upper 70s for the San Joaquin Valley, and in the low 80s for the Sierra Foothills and Mojave Desert.

Later today into tomorrow, a weak low pressure system is expected to move into southern California from the area of the Channel Islands, though this system will have minimal impacts to conditions for central California. After this perturbation passes through, a zonal pattern is favorable to set up over the western US, albeit with a slight deviation from the southwest. As a result, afternoon temperatures will warm one to two degrees from Sunday; the valley and desert areas of Kern County have a 70 to 80 percent probability to exceed 80 degrees. Stronger west-to-east winds with this pattern will start to bring stronger wind gust to the Mojave Slopes as well, though only with a 30 to 40 percent probability to exceed 40 mph Monday. Tuesday's conditions will be similar to Monday, albeit slightly cooler, but remaining above season averages.

The next pattern change will come Wednesday, when an Atmospheric River is favorable to move into northern California. For central California, impacts are expected on the weaker side, especially in the south valley, southern Sierra, and desert areas. There is a 60 to 70 percent probability for one-tenth inch or more in 24 hours ending 4 AM Thursday for Merced and Mariposa Counties, but with decreasing probabilities for these amounts further south. Madera and Fresno Counties have a 40 to 50 percent probability for one-tenth of an inch, and Kings/Tulare counties only 10 to 20 percent.

Snow levels with this system are expected at 7500-8000', but with the moisture with it focusing on the northern portion of our CWA, snowfall probilities are at their greatest in and around Yosemite National Park. There is a 70 to 80 percent probability for 1 inch or more of snowfall over 24 hours ending Thursday morning for these areas, but falling to 30 to 40 percent in the Sierra Nevada in Fresno County. However, there is a 40 to 50 percent probability to exceed 3 inches in Yosemite, expect for the highest elevations, which are at 60 to 70 percent.

While precipitation appears to be less of an impact for Kern County, this system is expected to bring stronger winds gusts to the Mojave Slopes, including the town of Mojave and California Highways 14, 58, and 178 on Wednesday. NBM ensemble output expresses a 70 to 80 percent probability for wind gusts greater than 40 mph, but a 30 to 40 percent probability to exceed 50 mph.

High pressure building in behind the aforementioned system will be favorable for fog development in the San Joaquin Valley in the late week period, especially for areas that receive rainfall.

AVIATION

40 to 50 percent chance for IFR conditions or lower at KVIS from 12Z to 15Z Sun. Otherwise, VFR conditions will prevail across central California through at least 06Z Mon.

AIR QUALITY ISSUES

On Monday November 3 2025, No Burning Unless Registered in Fresno, Kern, Madera, and Tulare Counties. Burning Discouraged in Kings and Merced Counties, and Kern (Greater Frazier Park Area) and Sequoia National Park and Forest.

CERTAINTY

The level of certainty for days 1 and 2 is high. The level of certainty for days 3 through 7 is medium.

Certainty levels include low...medium...and high. Please visit www.weather.gov/hnx/certainty.html for additional information and/or to provide feedback.

HNX WATCHES/WARNINGS/ADVISORIES

None.