Fossil Butte, Wyoming climate: Climate normals at a NOAA weather station
Fossil Butte's normal year runs from 5°F January nights to 83°F July afternoons, with 11.7 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 3.6°C, January lows of −15°C, July highs of 29°C, 298 mm of precipitation a year.
- NOAA stationFossil Butte
- Station IDUSC00483582
- Location41.84°N 110.77°W
- Elevation6,785 ft (2,068 m)
On October 23, the normal high in Fossil Butte is 53°F and the normal low 21°F, and the chance of measurable rain or snow is 23%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Fossil Butte.
- Jan 28° 5°
- Feb 31° 6°
- Mar 41° 16°
- Apr 52° 23°
- May 63° 30°
- Jun 74° 35°
- Jul 83° 42°
- Aug 82° 41°
- Sep 72° 32°
- Oct 57° 23°
- Nov 40° 14°
- Dec 29° 5°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like at Fossil Butte each month?
July is the warmest month, with normal highs of 83°F; January the coldest, with normal lows of 5°F. The most precipitation falls in May (1.54 in), the least in July (0.57 in).
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 28°F | 5°F | 16.2°F | 0.74 | 9 | <1 | 31 | 9 h 30 min |
| February | 31°F | 6°F | 18.3°F | 0.78 | 8 | <1 | 28 | 10 h 30 min |
| March | 41°F | 16°F | 28.4°F | 0.90 | 8 | <1 | 30 | 11 h 50 min |
| April | 52°F | 23°F | 37.5°F | 1.09 | 8 | <1 | 27 | 13 h 20 min |
| May | 63°F | 30°F | 46.3°F | 1.54 | 10 | <1 | 19 | 14 h 30 min |
| June | 74°F | 35°F | 54.4°F | 1.08 | 7 | 1 | 8 | 15 h 10 min |
| July | 83°F | 42°F | 62.6°F | 0.57 | 5 | 5 | 1 | 15 h |
| August | 82°F | 41°F | 61.2°F | 0.91 | 7 | 2 | 2 | 14 h |
| September | 72°F | 32°F | 52.0°F | 1.10 | 7 | <1 | 15 | 12 h 30 min |
| October | 57°F | 23°F | 40.1°F | 1.26 | 7 | <1 | 26 | 11 h 10 min |
| November | 40°F | 14°F | 27.2°F | 0.89 | 8 | <1 | 29 | 9 h 50 min |
| December | 29°F | 5°F | 16.9°F | 0.86 | 9 | <1 | 31 | 9 h 10 min |
| Year (annual) | 54°F | 23°F | 38.4°F | 11.72 | 93 | 8 | 247 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | −2°C | −15°C | −8.8°C | 19 mm |
| February | −1°C | −14°C | −7.6°C | 20 mm |
| March | 5°C | −9°C | −2.0°C | 23 mm |
| April | 11°C | −5°C | 3.1°C | 28 mm |
| May | 17°C | −1°C | 7.9°C | 39 mm |
| June | 23°C | 2°C | 12.4°C | 27 mm |
| July | 29°C | 5°C | 17.0°C | 14 mm |
| August | 28°C | 5°C | 16.2°C | 23 mm |
| September | 22°C | 0°C | 11.1°C | 28 mm |
| October | 14°C | −5°C | 4.5°C | 32 mm |
| November | 5°C | −10°C | −2.7°C | 23 mm |
| December | −2°C | −15°C | −8.4°C | 22 mm |
NOAA publishes no 1991-2020 snowfall normal for this station. The nearest record that keeps one, Kemmerer (12 miles away), gets 50 inches of snow in a normal year; elevation and distance can change that.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00483582; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
Which months are mildest at Fossil Butte?
Normal highs sit between 65°F and 85°F in June, July, August and September. Of those, July has the fewest days with rain (5).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00483582.
How hot and how cold does it get at Fossil Butte?
In a normal year in Fossil Butte, 8 days a year reach 90°F, 247 nights fall to 32°F or colder and 93 days bring measurable precipitation.
- Days at 90°F or more
- 8a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 247a normal year
- Days that stay below freezing
- 67high of 32°F or less
- Days with 0.01 inch of precipitation
- 93a normal year
Source: NOAA NCEI 1991-2020 annual normals, station USC00483582.
How sunny is it at Fossil Butte?
Over a year 80% of the sunlight that would reach the ground under clear skies gets through the clouds at Fossil Butte, 4.8 kWh per square metre a day. June is the sunniest month (86%) and December the cloudiest (70%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 74% | 2.3 |
| February | 74% | 3.2 |
| March | 74% | 4.4 |
| April | 75% | 5.6 |
| May | 77% | 6.6 |
| June | 86% | 7.8 |
| July | 86% | 7.4 |
| August | 85% | 6.5 |
| September | 85% | 5.3 |
| October | 81% | 3.7 |
| November | 75% | 2.5 |
| December | 70% | 1.9 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How many heating and cooling degree days does Fossil Butte record?
A normal year at Fossil Butte brings 9,718 heating degree days, 81% more than the median U.S. place (5,373), and 60 cooling degree days, 93% fewer than the median (908). Ten months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 1,069 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,513 | 0 |
| February | 1,308 | 0 |
| March | 1,136 | 0 |
| April | 825 | 0 |
| May | 580 | 0 |
| June | 319 | 3 |
| July | 111 | 36 |
| August | 138 | 20 |
| September | 392 | 1 |
| October | 770 | 0 |
| November | 1,136 | 0 |
| December | 1,491 | 0 |
| Year (annual) | 9,718 | 60 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00483582. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Have recent years at Fossil Butte been warmer than normal?
2025 averaged 42.8°F, 4.4°F above the 1991-2020 normal of 38.4°F. 4 of the 4 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 41.8°F | +3.4°F | 14.74 |
| 2022 | 38.7°F | +0.3°F | 11.05 |
| 2024 | 41.0°F | +2.6°F | 15.24 |
| 2025 | 42.8°F | +4.4°F | 13.82 |
Source: observed years: ACIS, station USC00483582. A year counts only with all twelve months complete.
How does Fossil Butte's climate compare?
Fossil Butte is warmer than 10 of the 71 places with their own NOAA record in Wyoming, and wetter than 30. Across the 7,247 U.S. stations with normals, its annual mean of 38.4°F is warmer than 4%.
In the Köppen classification computed from these normals, Fossil Butte is Dfb: continental, no dry season, warm summer. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Questions about Fossil Butte's climate
What is the coldest month at Fossil Butte?
January, with a normal high of 28°F and a normal low of 5°F. The warmest is July (83°F by day, 42°F at night).
Does it snow at Fossil Butte?
Yes. NOAA publishes no 1991-2020 snowfall normal for the station; the nearest record that keeps one, Kemmerer (12 miles away), records 50 inches of snow in a normal year.
What is the rainiest month at Fossil Butte?
May, with 1.54 in of precipitation in a normal year; the driest is July with 0.57 in.
What plant hardiness zone is Fossil Butte in?
The USDA's 2023 map puts Fossil Butte in zone 4b in ZIP code 83121, the nearest ZIP area. By the same method at the station, the coldest night of a typical year reaches −27°F (23 years, 1991-2020): zone 4a.
Nearby and next
- Wyoming climateThe statewide normals and every place in the state
- Sage (4 mi NNW), WY12 miles from this station, 38.6°F a year
- Kemmerer, WY12 miles from this station, 38.5°F a year
- Randolph, UT25 miles from this station, 39.4°F a year
- Laketown, UT29 miles from this station, 43.0°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made