Fossil Butte National Monument Park

National monument protecting exceptionally preserved Eocene fossil beds

High-elevation fossil beds in Wyoming preserve Eocene fish, plants and insects; researchers and visitors come for museum exhibits, guided fossil talks and low-traffic hiking across sagebrush plateaus near the ancient Fossil Lake deposits.

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Fossil Butte National Monument at a Glance#

Address: Fossil Butte National Monument, near Kemmerer, Wyoming, USA

Website: https://www.nps.gov/fobu

About Fossil Butte National Monument#

Fossil Butte National Monument in southwestern Wyoming protects exceptionally preserved Eocene fossil beds from the Green River Formation, famous for whole-fish fossils and detailed plant and insect remains. The unit preserves fossil-bearing lake sediments that document life about 50 million years ago.

Museum displays and the visitor center showcase numerous fish fossils and other articulated specimens such as insects and leaves; many are complete and finely detailed. Outdoor trails and overlooks let visitors view the gently sloping buttes and exposures where the lake-bed shales are exposed, and interpretive panels explain fossil collection and the ancient lake environment.

Fossil-rich shales were collected by 19th- and 20th-century fossil hunters and later studied by paleontologists; recognition of the scientific importance of these beds led to federal protection. The monument preserves in-situ exposures plus curated collections used for research and public education.

The monument lies in a rural part of Lincoln County near the town of Kemmerer in southwestern Wyoming, amid basin-and-range terrain and sagebrush steppe. The nearest towns provide services; the site is accessed by paved and gravel roads off regional highways.

  • Age and preservation: Fossils date to the early Eocene, roughly 50 million years ago, and include abundant complete fish specimens as well as plants and insects.
  • Access note: The park is remote; most visitors combine a stop with nearby Kemmerer or regional outdoor activities in southwestern Wyoming.

What to See#

  • Visitor Center and Exhibits: The visitor center displays fossil specimens from the Green River Formation and houses interpretive exhibits about Eocene lake environments and fossil preservation.
  • Fossil-bearing strata: Field exposures and quarry sites on park land reveal thinly bedded oil-shale layers that yielded exceptionally preserved Eocene fossils, including many complete fish specimens.

Tips for Visiting Fossil Butte National Monument#

  • Stop first at the visitor center to see the fossil displays and seasonal orientation talks - the center houses the best examples of Fossil Butte's famous fish and plants.
  • Plan your visit for a weekday or earlier in the morning during summer to avoid busier hours; the monument is compact and can feel crowded at peak times.
  • Remember that collecting fossils on-site is prohibited; enjoy the well-prepared specimens in the visitor center and on guided programs instead of searching in the field.

Best Time to Visit Fossil Butte National Monument#

Visit late spring through early autumn when roads, trails, and visitor services are most accessible and weather is milder.

Summer
June-August · 15-30°C
Warm days ideal for exploring trails and the visitor center; nights can be cool - this is the most accessible season.
Shoulder seasons (Spring/Autumn)
April-May, September-October · 0-20°C
Variable conditions with possible late or early snow; fewer visitors and quieter trails.
Winter
November-March · -20-5°C
Very cold with snow; many roads and outdoor activities may be limited or impassable.

Weather & Climate near Fossil Butte National Monument#

Climate

Fossil Butte National Monument's climate is classified as Cold Semi-Arid - Cold Semi-Arid climate with mild summers (peaking in July) and freezing winters (coldest in January). Temperatures range from -15°C to 27°C. Semi-arid with limited rainfall.

Temperature & Rainfall
Temperature Range
27°
Warmest Month
-15°
Coldest Month
Monthly Conditions

January

January is the coldest month with highs of -2°C and lows of -15°C. Light rainfall.

Comfort

-9°
Feels Like Freezing
-9°C
Temperature
-15° -2°

Weather

18 mm
Rainfall
3.1 m/s
Wind
Light Breeze

February

February is freezing with highs of 0°C and lows of -15°C. The driest month with just 16 mm.

Comfort

-8°
Feels Like Freezing
-8°C
Temperature
-15°

Weather

16 mm
Rainfall
3.1 m/s
Wind
Light Breeze

March

March is freezing with highs of 4°C and lows of -10°C. Light rainfall.

Comfort

-3°
Feels Like Freezing
-3°C
Temperature
-10°

Weather

18 mm
Rainfall
3.6 m/s
Wind
Light Breeze

April

April is cold with highs of 10°C and lows of -5°C. Light rainfall.

Comfort

Feels Like Cold
C
Temperature
-5° 10°

Weather

24 mm
Rainfall
3.9 m/s
Wind
Light Breeze

May

May is cold with highs of 16°C and lows of 0°C. The wettest month with 31 mm of rain.

Comfort

Feels Like Cold
C
Temperature
-1° 16°

Weather

31 mm
Rainfall
3.9 m/s
Wind
Light Breeze

June

June is cool with highs of 21°C and lows of 4°C. Light rainfall.

Comfort

12°
Feels Like Cool
12°C
Temperature
21°

Weather

29 mm
Rainfall
3.7 m/s
Wind
Light Breeze

July

July is cool with highs of 27°C and lows of 6°C. Light rainfall.

Comfort

17°
Feels Like Cool
17°C
Temperature
27°

Weather

22 mm
Rainfall
3.3 m/s
Wind
Light Breeze

August

August is cool with highs of 26°C and lows of 6°C. Light rainfall.

Comfort

16°
Feels Like Cool
16°C
Temperature
26°

Weather

23 mm
Rainfall
3.3 m/s
Wind
Light Breeze

September

September is cool with highs of 20°C and lows of 1°C. Moderate rainfall (30 mm).

Comfort

11°
Feels Like Cool
11°C
Temperature
21°

Weather

30 mm
Rainfall
3.2 m/s
Wind
Light Breeze

October

October is cold with highs of 14°C and lows of -4°C. Light rainfall.

Comfort

Feels Like Cold
C
Temperature
-4° 14°

Weather

22 mm
Rainfall
3.2 m/s
Wind
Light Breeze

November

November is freezing with highs of 4°C and lows of -10°C. Light rainfall.

Comfort

-3°
Feels Like Freezing
-3°C
Temperature
-10°

Weather

22 mm
Rainfall
3.2 m/s
Wind
Light Breeze

December

December is freezing with highs of -2°C and lows of -15°C. Light rainfall.

Comfort

-9°
Feels Like Freezing
-9°C
Temperature
-15° -2°

Weather

19 mm
Rainfall
3.0 m/s
Wind
Light Breeze