CHIEF JOSEPH DAM, WASHINGTON

NCDC 1971-2000 Monthly Normals

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
Monthly
Mean Max. Temperature (F) 33.8 40.9 53.8 64.9 73.3 80.9 89.0 89.2 79.0 63.5 45.2 34.4 62.3
Highest Mean Max. Temperature (F) 44.0 49.9 62.9 71.3 80.2 89.2 98.2 95.1 87.2 69.6 52.5 40.4 98.2
Year Highest Occurred 1990 1991 1992 1977 1992 1992 1985 1986 1998 1988 1990 1999 1985
Lowest Mean Max. Temperature (F) 23.8 33.2 45.0 59.0 67.6 74.1 81.0 80.5 71.5 59.6 31.8 25.0 23.8
Year Lowest Occurred 1979 1985 1971 1975 1984 1981 1993 1976 1985 1996 1985 1984 1979
Mean Temperature (F) 27.4 33.2 43.0 51.5 59.4 66.7 73.3 73.2 63.5 50.3 37.8 28.4 50.6
Highest Mean Temperature (F) 36.9 40.8 49.6 56.6 64.3 73.6 79.5 78.3 69.9 55.5 43.9 34.9 79.5
Year Highest Occurred 1990 1991 1992 1987 1993 1992 1985 1986 1998 1988 1990 1999 1985
Lowest Mean Temperature (F) 15.1 22.9 36.6 46.3 55.3 61.5 67.4 68.2 58.2 46.8 23.3 18.0 15.1
Year Lowest Occurred 1979 1985 1971 1972 1984 1981 1993 1976 1971 1984 1985 1984 1979
Mean Min. Temperature (F) 20.9 25.4 32.1 38.0 45.4 52.5 57.5 57.1 47.9 37.1 30.3 22.4 38.9
Highest Mean Min. Temperature (F) 32.9 33.5 36.5 42.7 49.5 58.3 62.3 61.6 52.9 41.9 36.3 29.3 62.3
Year Highest Occurred 1981 1992 1983 1987 1997 1997 1998 1977 1990 1979 1972 1999 1998
Lowest Mean Min. Temperature (F) 6.3 12.5 26.3 32.6 41.6 47.6 53.0 52.0 42.4 32.8 14.8 11.0 6.3
Year Lowest Occurred 1979 1985 1985 1972 1999 1994 1983 1980 1984 1984 1985 1984 1979
Mean Precipitation (in.) 1.25 1.09 0.96 0.65 0.92 0.84 0.60 0.44 0.48 0.56 1.44 1.64 10.87
Highest Precipitation (in.) 4.26 3.00 2.77 1.67 2.60 2.45 3.08 2.24 2.65 1.85 5.57 5.18 5.57
Year Highest Occurred 1995 1980 1995 1993 1990 1984 1993 1976 1986 1975 1983 1996 1983
Lowest Precipitation (in.) 0.02 0.03 0.06 0.00 0.01 0.07 0.00 0.00 0.00 0.00 0.05 0.20 0.00
Year Lowest Occurred 1977 1988 1979 1973 1992 1989 1985 2000 1999 1978 1976 1989 1973
Heating Degree Days (F) 1167. 892. 683. 407. 200. 77. 18. 13. 135. 455. 816. 1135. 5998.
Cooling Degree Days (F) 0. 0. 0. 1. 26. 127. 273. 265. 90. 1. 0. 0. 783.

Western Regional Climate Center, wrcc@dri.edu