Thermopolis, WY climate
Thermopolis has cold winters and warm summers, with very little rain. A typical July afternoon reaches 90°, a January night drops to 8°, and about 27 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Thermopolis feels like
Winter
Spring
Summer
Fall
Thermopolis 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 | 33° | 8° | 0.3" | 5.4" | 3 | 22 | 10° – 30° |
| February | 39° | 13° | 0.4" | 4.9" | 4 | 16 | 14° – 34° |
| March | 52° | 24° | 0.7" | 2.3" | 4 | 7 | 28° – 45° |
| April | 59° | 32° | 1.4" | 2.2" | 7 | 1 | 40° – 51° |
| May | 69° | 41° | 2.0" | 0.2" | 8 | 0 | 49° – 61° |
| June | 81° | 50° | 1.2" | 0 | 7 | 0 | 58° – 71° |
| July | 90° | 57° | 0.7" | 0 | 5 | 0 | 65° – 78° |
| August | 88° | 54° | 0.5" | 0 | 4 | 0 | 66° – 75° |
| September | 77° | 44° | 1.0" | 0.3" | 5 | 0 | 55° – 65° |
| October | 61° | 32° | 1.1" | 2.1" | 5 | 1 | 37° – 53° |
| November | 45° | 20° | 0.5" | 5.5" | 4 | 7 | 21° – 41° |
| December | 33° | 10° | 0.4" | 4.5" | 3 | 18 | 12° – 28° |
| Year | 60° | 32° | 10.1" | 27.4" | 59 | 72 |
“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 Thermopolis
Thermopolis gets 10 inches of rain and melted snow a year. May is the wettest month and January the driest. Rain or snow falls on about 59 days a year. Snow covers the ground about 72 days of the year.
About 152 frost-free days a year
In half of years the last 32° night comes by May 5 and the first one by October 5. That leaves about 152 frost-free days for gardens, shorter than 79% of U.S. towns.
Heating and cooling a home in Thermopolis
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Thermopolis, 90% of that work is heating and 10% 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 Thermopolis 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 Thermopolis averaged 1.2° warmer than the 1900s. The biggest change is in January (+3.2°). The shift is smaller than in 53% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Thermopolis’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 14° to 34°. August is the most reliable, staying within 9°.
Common questions about Thermopolis’s climate
What is the coldest month in Thermopolis?
January, with a typical high of 33° and a low of 8°.
What is the hottest month in Thermopolis?
July, with a typical high of 90° and a low of 57°. About 55 days a year reach 90°.
How much snow does Thermopolis get?
About 27 inches in a normal winter, most of it in November.
When is the first frost in Thermopolis?
In half of years the first 32° night comes by October 5, and the last spring frost by May 5.
What is the rainiest month in Thermopolis?
May, with 2.0 inches of rain and melted snow. The year totals 10 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Thermopolis itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Thermopolis, WY (1 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.