A Climatological Look at Dry Autumns
With a very dry start to the 2020-2021 California rainfall season, and no rain in the forecast through the end of the month, this is a look at what has happened in similar seasons. San Francisco, with the longest continuous rainfall record in the state back to 1849, is used for comparison.
To date, San Francisco has only had a paltry 0.54", which is just 12% of the normal July through November average of 4.55".
Below is a breakdown of the 16 seasons that had less than one-inch to begin the season. Of the previous 15 seasons, 5 of them finished the season above normal rainfall, and 10 finished below normal. Likewise, for seasons with a moderate La Niña, there was one season (1995) with above normal SF seasonal rainfall and two that ended below normal.
But caveat emptor, this data is climatology and NOT a forecast.
Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services