NATIONAL ARBORETUM DC, MARYLAND

Monthly Average Temperature (Degrees Fahrenheit)

(186350)

File last updated on May 16,
*** Note *** Provisional Data *** After Year/Month 201205
a = 1 day missing, b = 2 days missing, c = 3 days, ..etc..,
z = 26 or more days missing, A = Accumulations present
Long-term means based on columns; thus, the monthly row may not
sum (or average) to the long-term annual value.
MAXIMUM ALLOWABLE NUMBER OF MISSING DAYS : 5
Individual Months not used for annual or monthly statistics if more than 5 days are missing.
Individual Years not used for annual statistics if any month in that year has more than 5 days missing.
YEAR(S) JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANN
1948 ----- z ----- z ----- z ----- z ----- z ----- z ----- z 75.15 69.13 56.82 52.53 39.92 58.71
1949 43.56 44.46 47.90 55.50 66.13 74.20 80.87 77.02 67.45 63.44 48.43 42.12 b 59.26
1950 48.21 g 39.18 43.78 f 52.56 d 64.53 72.85 75.87 74.69 66.37 59.39 47.67 a 34.86 c 58.80
1951 39.50 38.54 a 46.44 d 55.10 64.73 72.75 77.68 c 75.84 70.97 60.82 44.69 c 42.05 b 57.43
1952 40.81 41.14 45.56 58.42 64.36 f 76.79 b 80.04 e 76.41 c 73.50 y 54.40 j 48.68 39.39 56.36
1953 41.95 a 43.20 ----- z ----- z ----- z 74.20 79.55 76.98 d 70.45 i 60.15 d 49.74 e 42.94 m 60.82
1954 37.00 j 44.68 46.05 61.05 62.23 c 74.87 d 78.77 76.08 73.48 62.55 45.40 37.56 e 60.25
1955 35.24 38.39 49.42 59.88 68.27 70.92 82.77 79.52 70.15 60.06 46.40 34.55 57.97
1956 35.02 b 41.95 44.19 54.21 a 64.89 74.12 76.92 76.03 68.53 60.05 48.55 a 46.06 57.54
1957 33.24 41.70 45.92 60.38 68.48 a 76.77 79.55 76.08 72.13 54.90 49.53 41.42 58.34
1958 33.97 30.66 41.23 56.27 65.03 71.32 78.66 75.32 68.43 58.39 50.50 32.47 55.19
1959 35.37 a 38.59 46.27 59.38 69.79 75.13 78.27 80.34 72.48 61.90 47.58 42.21 58.94
1960 38.16 38.55 35.31 61.48 63.60 73.37 76.10 77.98 70.47 57.82 49.37 31.53 56.14
1961 29.66 39.14 47.73 51.85 62.48 73.40 77.31 77.02 75.20 59.97 51.00 37.13 56.82
1962 35.58 35.30 44.24 57.07 69.24 74.08 75.55 77.08 67.48 60.23 44.78 32.79 56.12
1963 32.92 32.00 49.42 57.03 65.45 73.73 78.02 75.50 66.73 61.73 50.90 31.63 56.26
1964 36.94 36.74 48.15 54.05 67.63 75.28 78.47 75.00 69.58 54.60 51.20 41.27 57.41
1965 34.45 38.14 42.87 53.83 69.81 72.48 76.73 75.48 70.87 56.27 48.82 41.12 a 56.74
1966 32.29 36.61 47.66 52.15 63.92 74.37 80.05 77.58 66.68 55.82 48.27 37.69 56.09
1967 40.69 32.95 44.68 57.12 59.58 73.52 76.00 75.02 66.97 56.87 44.07 39.56 55.58
1968 31.89 34.22 49.45 56.77 62.77 73.30 77.92 78.79 69.95 60.69 50.37 37.11 56.94
1969 34.24 36.02 42.77 57.95 66.24 75.03 78.52 75.11 68.97 57.94 46.38 35.31 56.21
1970 29.68 36.95 42.27 54.90 67.71 73.48 76.85 76.95 74.22 61.92 48.52 39.15 56.88
1971 31.71 39.32 43.53 53.92 62.58 74.88 76.32 74.94 71.22 64.06 47.27 45.48 57.10
1972 38.90 35.72 45.35 53.73 63.76 69.60 77.02 74.82 70.75 55.06 45.60 43.08 56.12
1973 38.29 34.68 48.33 e 54.57 61.11 75.63 77.24 78.00 71.37 59.94 49.42 39.27 57.32
1974 39.74 35.27 46.58 56.77 63.66 69.90 77.08 76.24 68.25 54.73 a 49.71 b 40.66 56.55
1975 37.89 39.32 c 41.58 a 50.47 a 66.90 73.50 75.56 77.48 65.65 61.11 51.43 a 38.10 56.58
1976 31.10 a 44.48 b 48.79 57.97 61.90 75.05 75.65 73.89 67.43 52.00 41.65 32.37 a 55.19
1977 23.84 37.02 50.39 57.82 66.53 70.55 78.90 a 77.69 72.10 a 55.68 a 49.25 35.86 b 56.30
1978 29.35 28.05 41.31 54.78 62.84 73.30 75.63 a 78.52 a 70.38 55.73 49.18 39.89 54.91
1979 31.53 24.54 47.86 b 53.95 64.69 69.37 75.26 75.10 68.43 55.97 a 50.85 40.23 54.81
1980 34.16 31.13 b ----- z 53.80 65.63 71.35 78.66 78.42 72.60 55.79 43.02 a 38.07 c 56.60
1981 29.03 39.09 42.97 a 57.67 62.03 74.43 76.94 73.27 67.94 c 54.09 c 46.59 c 36.27 55.03
1982 26.24 36.59 43.40 51.92 67.16 70.78 77.58 72.24 67.70 57.00 49.23 43.60 55.29
1983 36.05 36.18 45.97 51.18 63.13 72.92 77.90 77.44 68.38 56.63 46.83 33.63 55.52
1984 29.19 41.05 39.24 52.27 62.63 73.65 74.50 75.08 65.17 62.08 a 43.78 44.11 55.23
1985 29.37 36.16 45.81 58.02 65.71 70.83 76.32 74.74 68.72 58.39 51.98 33.42 55.79
1986 33.52 33.70 45.10 a 55.67 64.90 72.07 75.95 72.16 67.62 59.10 44.37 37.31 55.12
1987 32.44 33.79 46.63 52.50 64.69 74.05 79.52 76.39 68.92 51.84 47.58 39.13 55.62
1988 28.21 36.00 45.34 52.90 63.71 72.72 80.00 78.03 64.63 50.35 45.18 34.08 54.26
1989 35.90 ----- z 52.00 x 52.52 61.71 74.27 75.66 72.85 66.50 54.71 ----- z 26.56 57.85
1990 41.81 43.61 a 48.56 54.90 62.97 72.78 78.53 74.97 68.13 61.48 50.40 42.76 58.41
1991 36.53 41.36 47.71 57.45 71.76 75.42 80.24 78.79 70.05 59.00 47.35 41.48 58.93
1992 37.32 39.81 43.60 54.38 61.15 70.55 77.85 72.35 67.70 54.03 47.13 38.05 55.33
1993 38.08 33.54 40.79 54.15 67.23 73.57 81.40 77.95 69.88 55.94 46.74 a 36.82 56.34
1994 27.40 35.50 42.77 59.50 61.13 77.22 79.77 73.76 67.45 54.94 51.42 42.19 56.09
1995 38.27 i 32.54 48.03 53.28 63.71 73.13 80.03 79.23 ----- z ----- z ----- z ----- z 61.42
1996 31.92 35.26 39.77 a 54.37 61.89 75.38 75.90 74.52 68.05 55.58 41.18 39.63 54.45
1997 33.47 40.55 45.45 51.07 60.21 70.27 77.71 75.56 67.97 57.27 44.23 39.68 55.29
1998 42.16 41.07 45.97 58.35 68.37 74.37 79.58 79.37 75.05 58.77 48.18 43.73 59.58
1999 37.18 38.36 42.82 55.98 66.35 74.95 83.05 79.56 69.22 55.34 51.97 39.71 57.87
2000 33.76 40.02 50.11 54.58 67.37 74.90 74.81 75.44 68.18 59.32 45.28 30.95 b 56.23
2001 32.89 39.21 42.23 56.78 66.11 76.03 75.85 79.42 68.85 58.35 51.75 b ----- z 58.86
2002 ----- z ----- z ----- z ----- z ----- z ----- z ----- z ----- z ----- z ----- z ----- z 36.30 a 36.30
2003 30.79 32.55 46.05 54.32 61.55 71.68 77.65 78.48 69.95 56.13 52.73 38.45 55.86
2004 29.79 36.24 47.37 56.17 71.44 72.85 77.87 75.95 70.70 57.16 50.48 38.84 57.07
2005 35.47 39.12 42.32 56.77 61.27 76.31 n 80.19 78.38 j 74.30 59.52 50.20 35.24 53.44
2006 41.58 f 38.27 46.79 59.20 64.27 74.10 80.31 80.00 67.05 56.27 49.85 43.50 59.96
2007 39.92 29.52 47.84 b 52.50 67.68 75.32 78.66 79.97 72.90 64.92 47.02 38.95 57.93
2008 36.71 38.86 46.55 56.88 62.79 76.50 78.81 75.08 71.05 57.18 46.65 39.55 57.22
2009 31.39 40.00 45.56 60.28 68.63 77.67 78.34 80.24 69.55 57.06 50.75 36.24 57.98
2010 33.44 32.64 49.26 60.02 67.45 79.13 81.74 78.53 72.87 60.16 48.88 f 33.50 58.98
2011 31.19 39.63 a 46.43 a 58.43 a 68.63 78.08 83.44 79.03 a 73.46 d 58.29 c 51.84 a 42.59 b 59.25
2012 38.74 43.21 a 55.79 57.57 b 67.30 u ----- z ----- z ----- z ----- z ----- z ----- z ----- z 48.83
Period of Record Statistics
MEAN 34.43 37.29 45.55 55.75 65.00 73.75 78.13 76.56 69.54 57.92 48.19 38.30 56.60
S.D. 4.32 4.11 3.29 2.74 2.87 2.12 2.05 2.12 2.48 3.04 2.78 3.98 1.33
SKEW 0.00 -0.54 -0.19 0.14 0.32 0.05 0.56 -0.07 0.42 0.02 -0.49 -0.44 0.47
MAX 43.56 44.68 55.79 61.48 71.76 79.13 83.44 80.34 75.20 64.92 52.73 46.06 59.58
MIN 23.84 24.54 35.31 50.47 59.58 69.37 74.50 72.16 64.63 50.35 41.18 26.56 54.26
NO YRS 59 62 59 62 60 61 62 62 60 61 60 61 51