YELLOWSTONE PK MAMMOTH, WYOMING

NCDC 1961-1990 Monthly Normals

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
Mean Max. Temperature (F) 27.5 33.0 38.7 47.9 59.1 69.5 79.6 77.6 66.5 54.4 38.2 28.5 51.7
Highest Mean Max. Temperature (F) 39.4 39.5 48.4 60.6 66.4 78.0 84.0 83.4 75.7 64.0 46.5 36.1 54.9
Year Highest Occurred 1981 1977 1986 1987 1969 1988 1989 1971 1990 1988 1981 1980 1987
Lowest Mean Max. Temperature (F) 17.8 23.1 31.4 35.2 51.4 63.3 73.8 70.1 55.2 46.3 27.7 18.4 47.8
Year Lowest Occurred 1979 1989 1965 1975 1975 1981 1987 1968 1961 1969 1985 1990 1975
Mean Temperature (F) 17.9 22.7 27.5 36.7 46.7 55.7 63.5 61.6 51.8 41.5 28.8 19.2 39.5
Highest Mean Temperature (F) 28.6 28.7 38.7 45.1 51.3 63.3 67.8 66.8 58.9 48.8 35.9 28.0 42.1
Year Highest Occurred 1981 1963 1986 1987 1987 1988 1989 1971 1990 1988 1981 1980 1981
Lowest Mean Temperature (F) 6.7 12.0 14.4 26.6 41.8 51.9 59.6 56.4 44.1 34.9 19.4 9.0 36.6
Year Lowest Occurred 1963 1989 1965 1975 1975 1975 1962 1968 1961 1969 1985 1990 1975
Mean Min. Temperature (F) 8.2 12.3 16.4 25.5 34.3 41.7 47.3 45.6 37.0 28.5 19.2 9.8 27.2
Highest Mean Min. Temperature (F) 18.0 20.0 29.0 29.6 37.9 48.5 51.5 50.2 42.9 33.5 25.3 19.8 30.2
Year Highest Occurred 1983 1961 1986 1985 1980 1988 1989 1983 1963 1988 1981 1980 1986
Lowest Mean Min. Temperature (F) -4.8 0.9 -2.7 18.0 30.3 37.4 43.2 40.6 29.9 23.4 11.0 -0.4 24.3
Year Lowest Occurred 1963 1989 1965 1975 1966 1976 1965 1976 1965 1969 1985 1990 1965
Mean Precipitation (in.) 1.14 0.72 1.01 1.00 1.93 1.94 1.54 1.53 1.41 1.04 1.08 1.00 15.34
Highest Precipitation (in.) 3.81 1.84 3.05 2.11 3.61 3.96 3.57 4.21 3.66 2.53 2.23 3.20 20.52
Year Highest Occurred 1968 1978 1974 1982 1988 1968 1987 1982 1961 1967 1970 1964 1982
Lowest Precipitation (in.) 0.05 0.16 0.12 0.07 0.12 0.43 0.37 0.14 0.05 0.00 0.29 0.02 11.08
Year Lowest Occurred 1981 1977 1969 1979 1979 1961 1990 1988 1979 1987 1972 1986 1979
Heating Degree Days (F) 1460. 1184. 1163. 849. 567. 290. 93. 153. 406. 729. 1086. 1420. 9400.
Cooling Degree Days (F) 0. 0. 0. 0. 0. 11. 47. 48. 10. 0. 0. 0. 116.

Western Regional Climate Center, wrcc@dri.edu