Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
846 FXUS66 KHNX 041735 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 1035 AM PDT Fri Jul 4 2025 && .KEY MESSAGES... 1. Temperatures slightly below season normals will extend across the region today and Saturday before a gradual warm up through the upcoming week. 2. Low RH values 15 to 25 percent will stretch across much of the San Joaquin Valley and Sierra Nevada this weekend with values 5 to 10 percent in the Mojave Desert. RH will decrease over the region later in the week with warming temperatures. 3. Breezy conditions in localized areas of the region this afternoon to evening. There is a 40 to 70 percent chance for wind gusts greater than 35 MPH in the Mojave Slopes and a 70 to 90 percent chance for 25 MPH along Pacheco Pass and at Lake Isabella. && .DISCUSSION... A broad area of low pressure passing through the Pacific Northwest region is causing (relatively) cooler air to entrain over central California from the central Pacific. As such, maximum temperatures this and tomorrow afternoon are anticipated to be a few degrees below the average for these dates. In fact, for this afternoon there is less than a 10 percent chance for much of the San Joaquin Valley to exceed 95 degrees but with isolated areas at 20 to 50 percent. The trough influencing the region will cause some stronger wind gusts across the region this afternoon and evening, primarily in normally-suceptable locations such as Pacheco Pass, Lake Isabella, and in the Mojave Desert Slopes. However, all locations are expected to remain below advisory criteria. To start next week, a weak cutoff upper low off the California coast and an upper high over the Four Corners will combine to cause southwest flow to develop over the region. This will result in a gradual warming trend through the week with typical minimum relative humidity values between 15 and 25 percent, except for the desert areas where values will be between 5 and 10 percent. In the latter part of the week, the aforementioned ridge is expected to slide westward, centering over California. The resulting pattern will bring a stronger increase in afternoon temperatures. There is a 50 to 70 percent chance for maximum temperatures greater than 100 degrees by Thursday in the San Joaquin Valley (and an 80 to 90 percent chance for Friday), and in addition there is a 20 to 40 percent chance for 105 degrees on Friday. These warmer conditions will seep into the desert areas as well, especially for Inyokern and Ridgecrest, where there is a 40 to 70 percent chance to exceed 110 degrees next Thursday through Sunday. The warmer temperatures will cause drier conditions to develop, with widespread minRH values between 10 and 20 percent. These values will continue the risk for grass fire development, however with the subsiding air aloft, winds will be relatively light in the valley areas, and mainly diurnal and terrain driven in the foothill, mountain, and desert areas. && .AVIATION... 18Z Update: VFR conditions will prevail for the next 24 hours across the Central California Interior. && .AIR QUALITY ISSUES... ISSUED: 07/03/2025 15:06 EXPIRES: 07/04/2025 23:59 None. && .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. && $$ public/aviation...McCoy weather.gov/hanford