Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
829 FXUS66 KHNX 100428 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 928 PM PDT Sat Aug 9 2025 .UPDATE... Aviation section updated. && .KEY MESSAGES... 1. Heat-wave started this weekend as triple digit heat expected through at least Tuesday. 2. There is a 60 to 90 percent chance of high temperatures of at least 100 degrees this weekend with a 20 to 40 percent chance of reaching 105 degrees. 3. Minor fire risk with widespread minimum relative humidity between 15 and 25 percent for the non-desert areas. Minimum relative humidity expected to be less than 10 percent in the Mojave Desert with breezy winds in the afternoon to evening. && .DISCUSSION... High pressure ridge now dominating the area as a heat-wave starts across Central California. Confidence in triple digit temperatures is high as ensemble consensus all lean in the direction of a three day heat-wave. While Probability of Exceedance (PoE) of reaching 105 degrees remains below 50%, except for a few areas, PoE of 100 degrees has widespread max percentages above 90% through Monday. These high PoE percentages increased confidence in the Heat Advisory currently in effect for the San Joaquin Valley and adjacent foothills. Little change is expected through Tuesday ahead of a disturbance that will begin a cooling trend by Midweek. Ensemble temperature analysis has been very consistent with the onset of the current heat-wave. Heat Advisory has been issued for a three (to possibly four) day stretch as max temperatures range from 100 to 105 degrees. The ridge pattern generating the heat-wave is also responsible for keeping winds across the region light. Except for local wind favored areas that become breezy during the afternoon period, will expect winds to remain light and diurnally driven. Until the ridge pattern breaks down due to a passing Pacific Northwest disturbance, the region will be dominated by a southwesterly wind flow. That flow will push monsoonal moisture east and avoid Central California. Without a southeasterly wind, the lack of moisture will keep the region dry. Long range ensemble analysis shows very good agreement in keep Southern California dry through day seven (next Saturday). && .AVIATION... 06Z Update: VFR conditions are expected in the San Joaquin Valley 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... Heat Advisory until 11 PM PDT Monday for CAZ300>317-319-321. && $$ public.....Molina/BSO aviation...JPK/BSO weather.gov/hanford