National Weather Service United States Department of Commerce
The December 2020 climate summaries for Big Piney, Buffalo, Casper, Greybull, Lake Yellowstone, Lander, Riverton, Rock Springs, and Worland are now available online.

Big Piney




Lake Yellowstone



Rock Springs


Monthly Summaries

The month of December was definitely warmer than normal. With the exception of Lake Yellowstone, every climate site was 1 degree or more above normal. Greybull, Buffalo and Worland were all better than 7 degrees warmer. Buffalo had its 1st warmest December and Greybull its 2nd warmest, although those records only go back to 1998. There was a cold spell around the 13th at many locations, and again on the 29th. These were the days of the coldest temperatures. The 9th and 22nd share the glory for the warmest days. The 22nd was also the day when the maximum wind gusts were reported at all sites except Rock Springs. Gust speeds ranged from 30 at Lake Yellowstone to 79 mph in Buffalo. Precipitation reports were a mixture of dry and wet for the monthly totals, with Rock Springs coming in at 2nd driest December...and their records go back to 1948. There was also a widespread snow event on the 14th and 15th across much of the state, although snow totals weren't  as impressive as other storms. There were a few records set at some of the climate locations.

Check  the CLMs for more specifics on daily records set at the various locations. See the links above for details for individual sites or click here for Water Year Precipitation summaries for more locations.

If you would like additional, or more in-depth climate information, please refer to our Climate Page. From the Riverton Home Page, hover over the "Climate and Past Weather" tab, and select the "Local" option. You can then find the Daily Climate Report (CLI), the Preliminary Monthly Climate Data (CF6), the Monthly Weather Summary (CLM), and the Regional Summary (RTP). The Daily Climate Report will have the weather data for the day (from midnight to 1159 pm). The Monthly Climate Data (CF6) will have this data for each day of the month, compiling all the daily data into one form. The Regional Summary will have temperature and precipitation data for various locations across the state, updated 3 times a day.