Mammoth, WY climate
Mammoth has cold, snowy winters and pleasant summers, with very little rain. A typical July afternoon reaches 81°, a January night drops to 11°, and about 72 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Mammoth feels like
Winter
Spring
Summer
Fall
Mammoth weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 30° | 11° | 1.0" | 11.5" | 11 | 31 | 13° – 25° |
| February | 34° | 11° | 0.9" | 11.5" | 11 | 27 | 11° – 30° |
| March | 43° | 18° | 1.2" | 10.9" | 11 | 19 | 23° – 37° |
| April | 50° | 25° | 1.5" | 7.8" | 11 | 6 | 32° – 43° |
| May | 61° | 33° | 2.0" | 1.7" | 13 | 1 | 41° – 51° |
| June | 70° | 40° | 2.1" | 0.3" | 13 | 0 | 48° – 61° |
| July | 81° | 45° | 1.3" | 0 | 9 | 0 | 53° – 70° |
| August | 80° | 43° | 1.2" | 0 | 9 | 0 | 56° – 66° |
| September | 70° | 36° | 1.3" | 0.6" | 9 | 0 | 49° – 57° |
| October | 54° | 27° | 1.4" | 4.7" | 10 | 3 | 31° – 48° |
| November | 39° | 18° | 1.3" | 9.9" | 10 | 16 | 20° – 37° |
| December | 29° | 11° | 1.1" | 12.6" | 12 | 28 | 14° – 25° |
| Year | 53° | 26° | 16.2" | 71.5" | 127 | 131 |
“Wet days” have at least 0.01" of rain or melted snow. “Snow on ground” counts days with 1" or more. The 30-year range is the coldest and warmest that month’s average temperature got between 1991 and 2020.
Rain and snow in Mammoth
Mammoth gets 16 inches of rain and melted snow a year. June is the wettest month and February the driest. Rain or snow falls on about 127 days a year. Snow covers the ground about 131 days of the year.
About 102 frost-free days a year
In half of years the last 32° night comes by June 3 and the first one by September 14. That leaves about 102 frost-free days for gardens, shorter than 99% of U.S. towns.
Heating and cooling a home in Mammoth
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Mammoth, 99% of that work is heating and 1% is cooling, so the furnace matters far more than the air conditioner.
Degree days measure how far each day’s average temperature falls below or rises above 65°, added up over a year. Source: NOAA station normals.
How Mammoth compares
Compared with every U.S. town and city on TownTapestry, each counted once.
Warmer than it used to be
The last 30 years in Mammoth averaged 1.1° warmer than the 1900s. The biggest change is in March (+3.1°). The shift is smaller than in 57% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Mammoth’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. February swings the most: between 1991 and 2020 its average temperature ranged from 11° to 30°. September is the most reliable, staying within 8°.
Common questions about Mammoth’s climate
What is the coldest month in Mammoth?
January, with a typical high of 30° and a low of 11°.
What is the hottest month in Mammoth?
July, with a typical high of 81° and a low of 45°. About 6 days a year reach 90°.
How much snow does Mammoth get?
About 72 inches in a normal winter, most of it in December.
When is the first frost in Mammoth?
In half of years the first 32° night comes by September 14, and the last spring frost by June 3.
What is the rainiest month in Mammoth?
June, with 2.1 inches of rain and melted snow. The year totals 16 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Mammoth itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Yellowstone Park Mammoth, WY (1 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.