Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
437 FXUS66 KHNX 071150 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 450 AM PDT Mon Sep 7 2026 .KEY MESSAGES... 1. One more day of below average temperatures for central California before a warming trend begins Monday, lasting through Thursday. 2. Medium probability (40 to 50 percent) for Major Heat Risk in the San Joaquin Valley on Thursday; 70 to 80 percent probability for triple-digits. 3. Medium probability (50 to 60 percent) for measurable rainfall in the Sierra Nevada on Wednesday. && .DISCUSSION... The last remmants of moisture from the light rainfall in the Mojave Desert earlier today remains over the Tehachapi Mountains as a small amount of clouds that will gradually move northeast out of Kern County. Clear skies will then prevail for that region by tomorrow morning. At the same time, the trough that has held over the Pacific Northwest will move eastwards as a large cut-off low is formed from the remains of Tropical System Marie and a trough pulled down from the Northwestern coast of the CONUS. This cut-off will form over the eastern Pacific and pull the ridge that was over the Gulf States west and lead to an increase in temperatures for our CWA from tomorrow into Thursday. This will result in Moderate Heat Risk becoming more widespread in the Valley and Desert starting Wednesday and continuing through Friday as probabilities for triple digits increase on those days, and large pockets of Major Heat Risk is expected on Thursday, the warmest day and the highest chances for triple digits at 70-80%. At the same time as these triple digit highs are expected for the Valley and Desert, a slight chance remains for isolated showers in the Sierra Nevada on Wednesday as additional moisture from the aforementioned tropical system may move through the Valley this time rather than over the Mojave Desert, though current chances for a wetting rain (0.1 inches) is around 10-30% at the highest elevations of the Sierra Nevada. A cooling trend is expected to begin by Friday as another trough moves down into the Pacific Northwest and pushes the ridge back east. This troughing is likely to continue into next weekend and early next week as below normal temperatures take a foothold once again. The main axis of this trough and all its potential energy would be further north around Washington and Oregon, meaning Central California is not expected to receive any rainfall from this system. Looking into the long term forecast, the Climate Prediction Center as our CWA under the leaning above normal temperatures category for both the 6 to 10 and 8 to 14 day outlooks, with normal being in the low 90`s for this time of year. && .AVIATION... VFR conditions expected for the next 24 hours. && .AIR QUALITY ISSUES... 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. && $$ EW/CM weather.gov/hanford