November 2021 Weather and Climate Summary Forecast

Summary:

• The western US experienced a cooler than average* October.
• An active storm track brought welcomed rains to many, with an extreme event bringing recording-breaking amounts over a few days leading to flooding and fire scar slides.
• Even with record-breaking rains, the drought is not over for most of the west. However, the first half of winter forecast is calling for drought conditions to improve for northern California into the PNW but remain in the southwest, Great Basin, and the Rockies.
• The November forecast favors a continuation of the cooler than average conditions seen in October. The storm track should keep precipitation events in play for the PNW and northern California, but little if any further south.
• Heat accumulation was minimal during the cool October. For most, the 2021 vintage ended up moderately above GDD, coming in near the average of the last five vintages. The exception was along the coast where cooler ocean temperatures kept temperatures near average or below average for most of the year.
• La Niña advisories are now in place and indicate that it will likely remain throughout the first half of winter, then transitioning back to neutral in spring. Forecast models run with La Niña conditions point to the PNW likely seeing a cooler/wetter winter, while California has high odds to be drier during the upcoming winter with near-average temperatures. The transition line is the unknown, with northern California being in between.

*Note that all references to normal or averages in this report are to the 1981-2010 climate normal for each weather/climate parameter unless stated otherwise. Also, note that the 1991-2020 climate normals are starting to become available across reporting agencies and will be used in this report when possible.

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