CHIEF JOSEPH DAM, WASHINGTON

NCDC 1961-1990 Monthly Normals

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
Mean Max. Temperature (F) 33.1 40.5 52.7 63.8 72.6 80.6 87.9 88.2 78.5 63.7 45.8 34.3 61.8
Highest Mean Max. Temperature (F) 43.6 50.8 59.1 71.1 78.4 87.8 98.1 95.1 87.6 69.8 52.5 39.6 65.5
Year Highest Occurred 1990 1967 1981 1977 1987 1986 1985 1986 1967 1988 1990 1966 1987
Lowest Mean Max. Temperature (F) 21.3 32.8 44.7 58.5 67.5 73.9 81.7 80.5 71.5 59.3 31.8 24.9 59.1
Year Lowest Occurred 1969 1985 1971 1963 1984 1981 1983 1976 1985 1968 1985 1984 1971
Mean Temperature (F) 26.3 32.7 42.3 51.2 59.1 66.9 73.0 72.9 63.3 50.7 38.3 28.3 50.4
Highest Mean Temperature (F) 36.2 40.6 46.6 56.7 63.2 72.2 79.8 78.6 70.4 55.9 43.9 34.8 53.4
Year Highest Occurred 1990 1967 1981 1987 1987 1986 1985 1986 1967 1988 1990 1966 1987
Lowest Mean Temperature (F) 14.4 22.4 36.5 46.4 55.5 61.7 67.7 67.2 58.5 47.2 23.3 17.8 47.9
Year Lowest Occurred 1979 1985 1971 1972 1984 1981 1983 1968 1971 1984 1985 1984 1985
Mean Min. Temperature (F) 19.5 24.8 31.9 38.5 45.7 53.1 58.0 57.5 48.1 37.6 30.8 22.4 39.0
Highest Mean Min. Temperature (F) 31.9 31.7 36.6 43.1 48.8 57.0 61.5 62.3 53.1 42.5 36.2 29.9 41.2
Year Highest Occurred 1981 1963 1983 1987 1985 1970 1990 1977 1967 1979 1972 1966 1987
Lowest Mean Min. Temperature (F) 5.3 11.9 26.4 33.1 42.7 49.2 53.7 52.7 42.8 33.4 14.7 10.6 36.2
Year Lowest Occurred 1979 1985 1985 1972 1974 1976 1983 1980 1984 1984 1985 1984 1985
Mean Precipitation (in.) 1.11 1.12 0.90 0.66 0.77 0.75 0.34 0.51 0.49 0.55 1.38 1.61 10.19
Highest Precipitation (in.) 3.15 4.23 2.53 1.62 2.60 2.45 1.78 2.24 2.65 1.85 5.57 3.51 21.57
Year Highest Occurred 1983 1961 1983 1963 1990 1984 1987 1976 1986 1975 1983 1987 1983
Lowest Precipitation (in.) 0.02 0.02 0.05 0.00 0.10 0.07 0.00 0.00 0.00 0.00 0.05 0.20 5.61
Year Lowest Occurred 1977 1967 1965 1973 1986 1989 1985 1986 1990 1978 1976 1989 1985
Heating Degree Days (F) 1200. 904. 704. 414. 191. 69. 10. 15. 136. 443. 801. 1138. 6025.
Cooling Degree Days (F) 0. 0. 0. 0. 8. 126. 258. 259. 85. 0. 0. 0. 736.

Western Regional Climate Center, wrcc@dri.edu