NATIONAL ARBORETUM DC, MARYLAND

Monthly Average Maximum 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 86.81 81.83 67.68 63.17 49.06 69.71
1949 53.29 55.14 59.29 68.33 78.74 85.47 91.26 88.45 80.33 74.61 60.17 51.42 70.54
1950 59.42 47.61 55.47 a 66.90 76.13 85.40 86.87 86.65 76.07 71.16 60.14 a 43.82 c 67.97
1951 49.52 49.59 a 58.18 c 68.40 77.84 84.20 89.60 a 88.10 83.07 72.65 56.14 b 51.70 a 69.08
1952 49.48 50.21 55.39 69.37 75.68 f 89.17 a 91.43 a 87.28 b 85.00 y 68.05 j 57.93 46.26 66.28
1953 50.30 a 53.29 ----- z ----- z ----- z 85.27 92.23 89.50 c 84.90 i 72.74 d 62.64 e 52.72 m 72.28
1954 47.18 i 56.07 56.39 73.37 73.75 c 86.96 d 92.06 86.71 86.13 73.84 54.37 45.15 e 71.35
1955 43.48 49.00 60.71 71.33 80.10 82.07 93.29 89.58 80.03 71.74 57.33 43.06 68.48
1956 42.70 a 51.76 54.48 65.93 a 78.45 86.47 86.97 86.77 79.60 69.68 57.79 a 54.90 67.96
1957 41.19 50.14 55.94 72.93 80.65 88.20 92.06 89.00 82.73 65.32 59.20 50.84 69.02
1958 42.39 39.14 49.58 67.67 76.45 82.57 88.61 86.61 80.53 70.29 60.90 41.90 65.55
1959 45.60 a 50.18 59.19 71.47 81.68 86.47 88.03 91.03 84.23 71.13 57.37 51.65 69.84
1960 45.65 46.45 44.45 75.10 74.77 84.60 87.03 88.45 80.73 68.19 61.07 42.58 66.59
1961 39.03 48.46 58.87 62.67 73.52 85.07 87.55 86.74 85.97 71.87 58.97 44.87 66.97
1962 44.45 43.54 54.45 68.00 81.39 84.30 86.10 88.84 78.27 71.19 53.67 41.65 66.32
1963 42.19 42.57 61.68 70.07 77.84 85.43 89.55 86.97 78.03 76.29 59.97 39.68 67.52
1964 47.58 45.72 59.61 65.23 80.13 87.57 89.42 86.16 81.70 66.94 63.43 49.84 68.61
1965 44.03 49.79 52.94 65.17 83.35 84.03 87.81 86.84 82.17 68.65 59.53 50.63 a 67.91
1966 39.90 45.32 60.13 62.37 77.03 86.67 92.61 89.39 76.87 68.45 59.47 45.71 66.99
1967 50.97 44.04 55.84 70.80 72.13 86.10 85.94 84.61 79.13 69.32 54.43 48.90 66.85
1968 41.45 43.76 63.26 70.43 74.29 85.37 88.65 89.77 82.63 70.61 59.20 45.23 67.89
1969 42.06 42.89 53.39 70.80 80.00 86.23 88.32 85.65 80.20 70.48 56.27 42.00 66.52
1970 38.65 46.71 52.10 66.93 80.77 85.37 87.52 87.74 86.27 72.13 57.43 48.23 67.49
1971 40.32 49.04 55.03 69.07 74.81 86.00 87.32 85.97 81.13 73.52 56.90 55.19 67.86
1972 48.00 45.45 55.90 66.33 75.58 79.87 86.87 86.03 81.97 66.42 54.67 51.45 66.54
1973 49.16 44.39 58.77 64.83 71.90 85.00 86.97 87.74 81.77 71.68 59.80 47.35 67.45
1974 47.97 45.50 57.90 68.53 73.94 79.60 87.71 85.10 78.33 67.50 a 61.07 a 50.48 66.97
1975 47.26 47.48 c 51.32 60.45 a 77.13 83.17 85.32 88.10 74.27 72.03 63.52 a 46.58 66.39
1976 40.20 a 56.75 a 61.13 70.67 73.29 85.27 85.97 84.35 78.50 61.13 52.00 41.90 a 65.93
1977 31.94 47.68 61.19 70.23 78.19 81.03 89.67 a 87.87 81.83 66.47 a 56.57 43.90 66.38
1978 37.81 35.79 50.32 66.13 72.58 84.07 85.40 a 87.37 a 81.00 68.35 59.47 50.68 64.91
1979 40.00 33.07 60.40 a 63.03 75.26 79.97 84.52 84.68 78.70 66.30 a 62.47 49.55 64.83
1980 42.03 39.93 b ----- z 62.80 77.06 82.93 89.35 89.52 84.63 66.52 52.10 a 47.61 c 66.77
1981 37.74 50.82 53.63 a 69.87 72.87 84.90 86.52 84.10 77.75 b 65.71 c 56.18 b 44.68 65.40
1982 35.29 46.04 53.29 64.47 79.29 80.17 88.10 83.42 79.37 68.84 61.17 52.84 66.02
1983 43.74 46.36 54.87 60.47 74.03 84.07 90.03 89.32 82.03 68.06 58.47 41.94 66.12
1984 39.29 50.66 48.94 61.20 74.06 85.63 84.68 85.87 78.33 72.45 56.37 55.71 66.10
1985 38.87 46.57 57.19 70.53 77.61 81.93 87.68 86.00 82.37 70.61 61.83 43.87 67.09
1986 43.97 42.36 57.63 a 69.00 77.26 83.50 85.13 82.97 79.63 73.26 56.00 47.97 66.56
1987 42.74 45.54 59.35 64.50 78.26 86.80 91.90 88.71 80.43 66.97 60.43 48.06 67.81
1988 40.03 46.72 57.19 64.13 75.55 86.00 93.55 90.77 78.30 65.42 58.93 47.55 67.01
1989 47.29 40.20 w 53.45 64.77 72.97 85.90 87.29 84.90 80.73 70.48 ----- z 34.77 68.26
1990 51.81 55.52 a 59.94 66.87 73.58 85.20 88.81 84.48 79.33 74.48 63.27 52.81 69.67
1991 45.90 52.18 57.29 68.03 83.19 86.97 90.29 89.48 81.40 70.94 57.10 50.71 69.46
1992 46.45 48.69 52.13 64.90 71.94 81.37 87.48 82.77 77.73 66.19 55.67 45.26 65.05
1993 46.00 43.21 49.55 65.20 78.94 85.27 92.39 89.52 80.37 67.16 58.28 a 45.32 66.77
1994 35.97 45.71 53.03 72.33 73.52 88.73 89.71 84.42 79.73 68.48 63.40 52.65 67.31
1995 46.87 42.50 59.48 66.90 74.55 83.37 91.03 90.90 ----- z ----- z ----- z ----- z 69.45
1996 41.19 43.52 48.80 a 65.37 71.48 86.20 85.19 84.65 76.97 66.29 49.97 46.87 63.87
1997 42.26 49.11 55.06 60.97 71.90 80.07 88.29 87.10 79.37 70.13 53.67 49.97 65.66
1998 51.32 50.75 56.13 70.73 79.23 84.20 91.61 92.00 87.90 70.42 61.13 54.48 70.83
1999 48.29 49.57 53.65 68.33 78.97 86.17 94.58 92.19 80.00 67.61 63.97 49.90 69.44
2000 43.84 51.38 62.29 65.40 80.16 86.00 86.00 86.35 79.53 72.90 57.37 41.26 67.71
2001 42.74 50.07 52.77 69.50 78.35 87.07 87.39 90.35 81.97 73.10 67.20 ----- z 70.96
2002 ----- z ----- z ----- z ----- z ----- z ----- z ----- z ----- z ----- z ----- z ----- z 44.03 44.03
2003 38.06 39.96 57.03 64.63 69.32 80.17 86.45 87.23 79.00 66.48 63.03 46.84 64.85
2004 38.03 45.55 58.10 65.80 81.55 81.73 86.13 84.68 79.70 66.77 60.00 47.90 66.33
2005 43.06 49.07 50.71 67.70 71.58 86.22 g 89.39 87.52 j 86.03 67.74 60.33 43.10 62.87
2006 50.44 f 47.43 56.87 70.93 74.90 83.97 89.42 90.00 75.27 66.19 58.93 53.58 69.77
2007 48.13 37.25 59.59 b 62.73 79.00 85.50 89.19 90.65 84.67 76.26 55.80 46.26 67.92
2008 45.16 48.31 57.26 67.20 73.29 87.17 88.52 85.26 80.57 68.13 54.70 47.90 66.95
2009 38.90 49.96 54.94 71.33 77.81 86.30 88.77 91.00 79.60 67.61 59.97 43.68 67.49
2010 41.77 39.64 58.35 72.07 77.65 88.93 91.58 87.65 84.23 70.68 59.83 f 41.10 68.51
2011 39.35 50.14 57.93 a 68.72 a 79.52 89.37 94.32 89.93 a 82.27 d 69.57 c 63.62 a 52.69 b 69.79
2012 48.84 54.29 a 68.06 69.18 b 77.20 u ----- z ----- z ----- z ----- z ----- z ----- z ----- z 60.09
Period of Record Statistics
MEAN 43.79 47.02 56.19 67.41 76.52 84.80 88.76 87.44 80.72 69.57 58.77 47.34 67.24
S.D. 4.96 4.81 4.11 3.42 3.30 2.43 2.52 2.33 2.77 3.01 3.42 4.38 1.53
SKEW 0.40 -0.45 -0.15 -0.13 0.03 -0.45 0.44 -0.03 0.36 0.05 -0.17 -0.19 0.36
MAX 59.42 56.75 68.06 75.10 83.35 89.37 94.58 92.19 87.90 76.29 67.20 55.71 70.83
MIN 31.94 33.07 44.45 60.45 69.32 79.60 84.52 82.77 74.27 61.13 49.97 34.77 63.87
NO YRS 61 62 61 62 60 61 62 62 60 61 60 61 52