# Boysen State Park

Boysen State Park is a public recreation area surrounding the Boysen Reservoir, an impoundment of the north-flowing Wind River, in Fremont County, Wyoming. The state park covers more than 35,000 acres (14,000 ha) at the south end of the Owl Creek Mountains at the mouth of the Wind River Canyon.

## History

The park was established in 1956 following completion of the Boysen Dam in 1951. It is named for Asmus Boysen, who built the site's first dam in 1908. Part of the original dam can still be seen.

## Climate

According to the Köppen Climate Classification system, Boysen Dam has a cold semi-arid climate, abbreviated "BSk" on climate maps. The hottest temperature recorded at Boysen Dam was 108 °F (42 °C) on July 4, 1954, while the coldest temperature recorded was −39 °F (−39 °C) on January 31, 1979.
Climate data for Boysen Dam, Wyoming, 1991–2020 normals, extremes 1948–present :
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Record high °F (°C) | 70 (21) | 69 (21) | 77 (25) | 88 (31) | 97 (36) | 103 (39) | 108 (42) | 104 (40) | 100 (38) | 89 (32) | 71 (22) | 65 (18) | 108 (42) |
| Mean maximum °F (°C) | 48.9 (9.4) | 55.5 (13.1) | 67.8 (19.9) | 77.9 (25.5) | 86.2 (30.1) | 94.3 (34.6) | 100.1 (37.8) | 97.8 (36.6) | 92.4 (33.6) | 80.3 (26.8) | 63.6 (17.6) | 52.0 (11.1) | 100.4 (38.0) |
| Mean daily maximum °F (°C) | 29.7 (−1.3) | 37.2 (2.9) | 50.4 (10.2) | 58.7 (14.8) | 68.7 (20.4) | 80.8 (27.1) | 90.5 (32.5) | 88.5 (31.4) | 76.5 (24.7) | 60.4 (15.8) | 44.4 (6.9) | 31.3 (−0.4) | 59.8 (15.4) |
| Daily mean °F (°C) | 17.5 (−8.1) | 24.0 (−4.4) | 36.8 (2.7) | 45.7 (7.6) | 55.7 (13.2) | 66.3 (19.1) | 75.1 (23.9) | 73.0 (22.8) | 61.8 (16.6) | 47.5 (8.6) | 33.2 (0.7) | 20.1 (−6.6) | 46.4 (8.0) |
| Mean daily minimum °F (°C) | 5.4 (−14.8) | 10.7 (−11.8) | 23.3 (−4.8) | 32.7 (0.4) | 42.7 (5.9) | 51.8 (11.0) | 59.7 (15.4) | 57.4 (14.1) | 47.1 (8.4) | 34.5 (1.4) | 22.1 (−5.5) | 8.9 (−12.8) | 33.0 (0.6) |
| Mean minimum °F (°C) | −11.7 (−24.3) | −8.1 (−22.3) | −5.3 (−20.7) | 19.2 (−7.1) | 30.2 (−1.0) | 40.7 (4.8) | 51.2 (10.7) | 48.0 (8.9) | 35.3 (1.8) | 20.4 (−6.4) | 6.6 (−14.1) | −8.1 (−22.3) | −16.4 (−26.9) |
| Record low °F (°C) | −39 (−39) | −36 (−38) | −21 (−29) | 2 (−17) | 20 (−7) | 27 (−3) | 41 (5) | 38 (3) | 16 (−9) | −3 (−19) | −15 (−26) | −36 (−38) | −39 (−39) |
| Average precipitation inches (mm) | 0.22 (5.6) | 0.32 (8.1) | 0.57 (14) | 1.10 (28) | 2.08 (53) | 1.01 (26) | 0.75 (19) | 0.46 (12) | 0.96 (24) | 0.90 (23) | 0.28 (7.1) | 0.37 (9.4) | 9.02 (229.2) |
| Average snowfall inches (cm) | 2.8 (7.1) | 3.2 (8.1) | 3.8 (9.7) | 1.3 (3.3) | 0.1 (0.25) | 0.0 (0.0) | 0.0 (0.0) | 0.0 (0.0) | 0.1 (0.25) | 0.8 (2.0) | 1.8 (4.6) | 2.2 (5.6) | 16.1 (40.9) |
| Average precipitation days (≥ 0.01 in) | 2.9 | 3.5 | 4.1 | 5.9 | 8.1 | 5.9 | 5.0 | 4.1 | 4.8 | 4.3 | 3.3 | 3.7 | 55.6 |
| Average snowy days (≥ 0.1 in) | 1.8 | 2.1 | 2.0 | 0.9 | 0.1 | 0.0 | 0.0 | 0.0 | 0.1 | 0.8 | 1.3 | 2.0 | 11.1 |
| Source 1: NOAA ||||||||||||||
| Source 2: National Weather Service ||||||||||||||

## Activities and amenities

The park offers multiple campgrounds, boat launches, and a privately operated marina. Game fish found in the reservoir include walleye, sauger, perch, crappie, ling, rainbow, cutthroat, and brown trout.