Weather Watch 18-Day Analysis for East Central and South San Joaquin Valley

By WeatherAg Chief Meteorologist Scott Borgioli

Monday, April 22, 2024 through May 9, 2024

LOWS (through May 9):

  • No temperature concerns; lows +/- 0-4° of seasonal average

HIGHS (through May 9):

  • Wednesday (Apr 24) to Thursday May 2: +/- 3-7° of seasonal averages
  • May 3-May 9: odds favor +/- 0-4° of seasonal averages

General Summary Through May 9 (based on data at this time):


  • The tail end of a low-pressure system affecting the PacNW will clip NorCal. At this time, I expect local precipitation impacts to remain north of Madera, with generally partly cloudy skies and wind gusts of 10-20 mph throughout the valley. The breeziest period looks to be Thursday afternoon/evening and Friday from sunrise to sunset. Regarding precip, if the system ends up sliding just a bit farther south, there would then be a few isolated showers north of Pixley on Friday until sunset. A slight chance of a thunderstorm would also exist (again, if the system sags farther south than currently expected).

Saturday (Apr 27)-May 2 (preliminary):

  • High pressure in the Pacific will likely keep storm systems aimed into the PacNW and north of Sacramento. That said, from April 30 to May 2, a cut-off low-pressure system will be just offshore of WA/OR, bringing showers into far NorCal (around Redding northward). Locally, I expect us to see just some passing high clouds, light breezes (~10 mph or less), and temps within 4° of seasonal averages. There’s a slight possibility (but most improbable) that high pressure may ultimately be positioned to allow this cut-off low-pressure system to slide farther south and into NorCal and possibly the northern parts of CenCal.

Fri May 3-Thurs May 9 (preliminary):

  • Odds lean towards low-pressure systems affecting the PacNW and north of Sacramento, with high pressure in the Pacific that’s west/well to the west of SFO. Strong inland high pressure is not seen across the west during this period. Therefore, temperatures are expected to be within 5° of seasonal averages (as a whole) during this defined period. The weather during this time frame will likely have varying amounts of clouds at times (due to the proximity of low-pressure systems affecting the PacNW/far NorCal) and some breezy periods with wind gusts of 10-20 mph at times in spots across the valley. Chances for precipitation are extremely low, but not zero, due to the possibility that a low-pressure system or two could become cut off and sneak into parts of CenCal (especially if the ultimate location(s) of high pressure align just right).

PRECIPITATION PROBABILITIES (preliminary, based on current signals)

  • May: 50-70% of average
  • Sept-Nov: 40-60% of average due to expected “moderate” strength La Nina

TEMPERATURE ANOMALY PROBABILITIES (preliminary, based on current signals)

  • Odds favor +/- 5° of average mean temperatures as a whole through May; above average for June/July


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