The following tables present IEM computed monthly data summaries based on
daily data provided by or computed for the IEM. A download interface
exists for the daily summary information. The climatology is provided by the
nearest NCEI climate station (USW00026615) within the current 1991-2020
dataset.
To load shown data into Microsoft Excel,
highlight the table information with your mouse and then copy/paste into Excel.
Precipitation Totals [inch]
Year
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
1948
M
M
M
M
M
M
0.00
0.00
0.00
0.00
0.00
0.00
1949
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1950
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1951
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1952
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1953
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1954
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1955
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1956
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1957
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1958
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1959
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1960
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1961
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1962
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1963
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1964
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1965
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1966
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1967
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1968
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1969
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1970
M
M
0.00
0.00
M
M
M
M
M
M
M
M
1971
M
M
M
M
M
M
M
M
M
M
M
M
1972
M
M
M
M
M
M
M
M
M
M
M
M
1973
0.00
M
M
M
M
M
M
M
M
M
0.00
0.00
1974
0.00
0.00
0.00
0.00
0.00
0.00
M
M
0.00
0.00
0.00
0.00
1975
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1976
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1977
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1978
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1979
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1980
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1981
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1982
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1983
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1984
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1985
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1986
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1987
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1988
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1989
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1990
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.14
0.00
0.00
0.05
0.00
1991
0.00
0.00
0.03
0.00
0.00
0.19
0.06
0.11
0.00
0.00
0.00
0.00
1992
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1993
8.64
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1994
0.01
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1995
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1996
0.00
0.00
0.00
0.00
0.00
0.00
14.66
14.93
3.86
0.51
1.53
0.20
1997
0.24
0.41
0.02
0.17
0.86
0.70
0.67
2.96
1.33
15.57
0.24
0.18
1998
0.10
0.00
0.86
0.39
2.57
1.67
3.16
5.14
3.20
1.82
0.11
0.08
1999
0.05
0.00
39.57
10.41
0.82
2.71
2.01
1.91
1.91
0.78
0.00
0.13
2000
0.53
0.09
0.12
0.10
17.34
0.73
1.66
1.25
1.25
0.13
0.23
0.18
2001
0.19
0.24
10.02
0.83
0.36
0.64
1.26
2.22
0.84
0.27
0.00
0.15
2002
6.70
0.08
13.26
0.23
0.47
0.97
8.99
0.34
9.99
0.06
9.97
9.59
2003
19.98
0.54
9.41
0.60
0.92
10.57
41.43
18.98
19.42
19.86
2.27
0.17
2004
7.54
20.14
10.07
10.26
1.96
2.43
1.17
0.94
1.75
2.21
0.93
24.81
2005
20.25
29.99
20.00
0.00
0.79
3.09
4.09
2.79
4.48
1.67
0.19
0.88
2006
0.00
0.55
0.23
0.37
9.49
10.43
2.09
4.53
2.54
2.99
0.30
0.04
2007
0.05
0.15
0.00
9.98
1.27
1.89
1.65
3.84
6.10
6.81
0.60
0.32
2008
0.24
0.20
8.96
9.70
0.65
9.91
2.87
1.06
28.70
0.45
0.00
0.13
2009
0.79
0.22
0.24
2.05
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
2010
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
2011
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
2012
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.26
2013
0.39
0.00
0.18
0.00
0.68
0.99
3.12
3.99
3.82
4.83
1.71
0.92
2014
0.51
0.34
0.02
0.02
1.47
1.02
1.92
2.46
1.27
0.40
0.62
0.54
2015
0.07
0.49
0.43
0.32
0.98
0.83
2.08
2.89
5.18
1.32
1.49
0.02
2016
0.01
0.20
0.57
0.55
2.77
2.97
4.65
6.47
4.91
1.57
0.25
0.92
2017
0.39
0.33
0.02
0.01
1.21
0.63
1.84
4.77
3.53
4.10
0.80
0.43
2018
0.02
0.95
0.62
0.82
1.48
1.67
2.53
5.11
2.12
1.11
0.20
0.69
2019
0.08
0.39
0.63
0.28
1.24
1.12
1.18
3.88
5.28
2.75
1.72
0.12
2020
0.14
0.50
0.70
2.16
0.56
2.37
1.67
1.32
1.90
1.19
1.04
0.29
2021
0.48
0.25
0.95
0.72
0.19
1.90
5.92
3.56
3.80
2.87
0.01
4.23
2022
0.68
2.42
1.02
0.04
0.25
0.64
5.03
5.40
3.26
2.47
1.68
0.22
2023
0.83
0.41
0.37
0.20
1.07
1.32
2.76
2.18
1.99
0.75
1.18
0.23
2024
0.05
0.83
0.48
0.40
0.89
0.70
2.47
3.43
2.47
0.69
0.46
0.08
2025
1.20
0.27
0.34
0.54
0.36
0.90
1.52
2.45
2.21
2.90
0.43
0.24
2026
0.12
0.65
0.00
1.18
0.96
0.30
2.57
1.99
M
M
M
M
NCEI Climatology
0.77
0.91
0.74
0.79
1.21
1.77
2.57
3.36
2.89
1.84
1.80
1.06
Average Wind Speed [MPH]
Year
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
1948
M
M
M
M
M
M
7.0
5.5
6.7
8.2
7.2
6.6
1949
7.0
7.0
8.5
6.8
4.8
7.2
5.2
7.2
7.4
7.3
8.2
5.7
1950
4.7
9.2
8.6
7.8
8.1
7.0
5.4
5.7
8.0
6.1
6.0
5.9
1951
6.3
8.9
7.6
8.2
8.3
7.9
6.7
6.3
6.7
8.2
5.3
6.6
1952
7.5
8.1
8.1
7.4
5.9
6.9
6.4
6.5
6.1
6.9
8.3
3.9
1953
8.3
7.6
5.2
6.8
6.4
7.2
5.8
6.3
6.3
6.7
6.7
5.3
1954
5.4
5.0
8.7
8.0
7.7
6.0
6.2
7.6
7.0
5.8
7.9
5.4
1955
9.2
8.3
9.6
9.7
7.8
8.5
6.6
7.8
6.9
7.9
6.1
7.8
1956
7.2
6.8
8.7
8.0
8.4
7.1
6.4
5.8
7.4
6.6
3.9
4.1
1957
5.9
5.3
6.1
6.5
5.6
3.8
4.2
3.9
5.5
5.1
4.4
3.6
1958
4.5
6.5
6.9
5.6
7.2
6.3
4.3
3.9
4.9
5.4
4.9
4.0
1959
4.9
7.2
3.9
6.8
5.7
4.2
5.8
4.5
5.3
4.8
6.6
4.8
1960
7.2
7.6
8.4
6.7
6.3
5.3
4.4
4.8
6.0
6.8
6.5
7.0
1961
6.7
5.3
5.5
7.6
6.0
5.2
6.0
5.6
6.0
6.4
8.2
5.3
1962
5.4
5.9
7.1
7.6
6.4
6.1
4.0
5.4
5.5
7.0
4.8
4.8
1963
7.2
7.0
7.8
7.1
5.8
6.5
4.4
7.0
5.0
6.3
4.3
6.7
1964
4.5
7.2
5.9
7.4
6.7
4.7
3.5
5.7
8.3
7.1
7.6
6.7
1965
M
M
M
11.6
M
M
M
8.0
M
M
M
M
1966
M
M
M
15.3
M
M
6.5
M
M
M
M
M
1967
M
M
M
M
M
M
4.6
7.2
9.6
M
3.6
M
1968
M
7.5
M
M
10.5
7.7
5.3
M
M
M
M
M
1969
M
M
M
13.2
10.8
10.2
6.8
8.0
7.4
8.2
M
M
1970
M
M
M
M
M
M
M
M
M
M
M
M
1971
M
M
M
M
M
M
M
M
M
M
M
M
1972
M
M
M
M
M
M
M
M
M
M
M
M
1973
11.7
M
M
M
M
M
M
M
M
M
4.2
6.1
1974
6.2
8.1
M
7.5
7.9
5.9
M
M
10.4
6.6
5.5
5.8
1975
6.8
9.8
7.1
10.4
11.9
8.1
7.6
5.6
7.7
8.4
6.4
5.9
1976
7.7
7.2
7.0
6.7
6.6
6.3
6.7
6.3
6.0
7.3
5.5
5.9
1977
8.1
6.9
7.2
6.6
5.8
5.2
5.0
5.1
6.0
6.3
5.5
9.4
1978
6.9
8.3
7.3
8.3
6.2
7.0
5.8
5.2
6.1
8.2
8.4
8.5
1979
7.6
6.3
7.7
9.7
7.3
6.2
5.8
6.2
7.2
7.0
8.1
6.5
1980
7.8
8.8
8.4
6.6
8.9
6.5
6.0
6.4
8.4
6.6
6.4
6.6
1981
6.0
7.9
7.4
7.1
6.8
5.6
5.8
6.6
5.7
7.0
6.4
5.2
1982
5.9
6.3
7.5
6.7
6.5
7.6
6.1
4.8
6.3
6.3
6.8
5.2
1983
8.1
7.4
6.7
7.3
5.9
5.7
5.8
5.4
6.6
7.6
8.4
7.9
1984
5.0
5.7
6.9
6.9
6.0
5.3
5.9
6.0
5.8
5.3
4.9
6.7
1985
7.6
6.8
7.0
5.3
8.2
5.8
4.9
8.0
8.1
7.3
8.3
8.1
1986
4.9
7.6
7.4
7.2
7.7
7.7
6.5
7.5
8.5
5.4
7.8
8.1
1987
7.4
7.1
7.3
7.2
6.5
7.3
5.2
5.9
6.7
6.8
5.5
6.0
1988
6.9
6.8
7.0
8.7
6.4
5.9
5.5
5.9
5.5
6.8
5.3
8.3
1989
5.5
9.8
6.4
7.1
7.0
6.4
5.2
5.3
7.1
7.7
5.3
6.6
1990
5.7
5.3
6.2
5.9
7.1
4.4
5.0
5.3
6.2
5.3
5.3
7.0
1991
5.2
5.4
5.9
4.9
5.5
6.4
4.3
4.6
6.6
7.0
3.9
4.2
1992
2.7
3.2
4.8
6.0
5.3
5.8
3.7
5.1
5.3
4.7
5.4
4.9
1993
6.6
6.8
7.1
3.8
6.0
4.8
4.5
5.0
5.7
5.3
6.6
5.7
1994
4.6
6.3
6.6
6.1
6.1
4.7
4.7
4.8
5.0
5.2
6.7
7.4
1995
4.4
7.2
5.9
6.1
6.1
4.8
4.2
3.5
4.6
6.1
3.9
4.5
1996
5.7
7.0
6.7
6.9
5.8
5.6
4.4
4.3
4.8
5.5
4.7
3.1
1997
4.8
6.4
6.4
6.5
6.0
4.1
4.0
5.0
4.6
4.3
5.8
4.3
1998
5.1
3.1
9.4
6.6
7.9
5.0
3.8
4.9
4.8
5.9
4.5
4.2
1999
5.1
5.1
5.2
7.1
5.4
3.9
3.8
4.5
5.2
3.9
4.9
3.6
2000
4.8
8.1
6.8
6.1
4.9
4.9
3.8
5.0
4.0
5.8
7.9
6.9
2001
6.7
6.8
6.8
7.0
5.7
4.3
4.3
4.2
4.2
5.6
4.2
3.0
2002
6.1
6.4
6.2
6.3
5.4
4.6
4.7
3.1
4.9
7.7
5.3
3.7
2003
4.3
6.3
7.0
6.1
5.7
4.9
4.6
3.3
4.5
5.1
5.3
4.3
2004
3.7
5.6
6.0
5.6
4.7
4.0
4.3
3.5
4.2
5.9
7.3
5.2
2005
5.1
6.4
5.8
5.9
5.2
3.9
4.2
3.8
4.7
4.5
4.7
3.8
2006
2.6
8.6
6.9
6.3
5.9
5.4
4.0
3.0
3.9
6.1
5.7
3.1
2007
6.7
5.3
6.5
5.5
4.4
3.9
2.8
3.6
4.6
5.0
6.2
4.7
2008
4.5
4.9
5.4
6.1
5.6
3.3
4.2
3.0
3.9
4.0
3.3
6.3
2009
4.0
6.0
7.4
6.9
5.7
5.1
5.2
3.6
3.8
6.5
3.7
5.8
2010
5.7
5.3
4.8
6.0
4.6
4.2
3.9
3.3
5.1
4.8
5.1
5.8
2011
7.4
6.3
6.6
6.6
6.6
5.9
4.3
3.4
4.2
4.8
5.9
5.9
2012
5.0
7.5
5.4
5.2
5.3
4.7
4.9
4.3
5.7
7.0
7.2
4.8
2013
6.4
4.8
6.1
5.6
5.9
5.3
4.1
4.5
5.6
7.0
4.9
5.6
2014
6.4
7.6
5.2
6.1
5.5
4.3
4.3
4.0
5.5
6.1
6.1
5.0
2015
3.4
5.7
4.2
6.2
6.7
5.1
4.6
4.4
4.7
5.2
5.8
5.8
2016
7.3
5.1
5.8
6.3
5.7
4.5
3.9
3.7
4.0
7.6
3.3
5.5
2017
3.5
3.9
4.5
4.8
4.6
4.9
3.6
4.8
4.6
5.9
5.3
6.5
2018
5.8
6.4
5.7
6.6
7.7
6.2
6.7
6.1
5.4
8.6
6.1
5.6
2019
6.8
10.6
7.4
6.4
7.0
4.6
4.3
4.5
7.1
6.5
6.2
5.2
2020
4.8
7.0
6.5
6.9
5.9
4.8
4.2
4.3
6.1
5.7
7.7
5.8
2021
4.2
5.6
8.2
7.3
7.1
6.8
6.7
6.2
5.2
6.5
2.3
8.8
2022
4.5
5.9
6.8
7.4
6.4
5.4
5.7
6.0
6.5
5.4
6.0
5.9
2023
4.0
6.3
8.9
5.8
8.0
7.7
6.8
6.3
5.1
5.1
6.6
4.9
2024
6.8
7.1
7.9
8.8
6.7
6.4
6.4
8.5
5.7
6.4
4.6
4.5
2025
7.7
5.1
5.2
6.5
5.7
7.5
6.5
7.4
4.7
7.3
4.7
5.5
2026
3.8
6.3
5.1
7.7
7.9
5.9
6.5
7.1
M
M
M
M
NCEI Climatology
M
M
M
M
M
M
M
M
M
M
M
M
Average Daily High Temperature [F]
Year
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
1948
M
M
M
M
M
M
58.39
56.74
47.30
32.42
12.13
6.14
1949
14.38
10.36
30.23
30.10
44.56
55.93
64.48
56.65
53.90
36.88
29.80
5.97
1950
17.35
-0.07
30.23
36.37
49.52
58.37
65.90
63.61
53.00
37.68
20.40
11.19
1951
-0.52
19.39
10.45
39.10
55.35
62.03
62.90
59.00
51.83
37.74
25.13
11.94
1952
6.13
12.52
22.06
30.77
43.77
60.77
61.71
59.13
50.03
39.84
31.77
6.61
1953
2.16
14.64
16.81
42.17
55.13
65.13
70.77
59.32
52.53
33.48
21.77
12.06
1954
-0.45
1.61
27.65
37.87
57.52
65.40
62.58
59.68
51.10
39.97
26.43
-3.93
1955
26.69
6.00
25.94
28.13
49.90
54.30
62.23
58.52
50.67
31.00
14.47
9.48
1956
0.00
8.55
19.58
35.30
49.37
62.00
65.26
61.58
51.20
28.55
7.67
-6.13
1957
24.48
14.43
28.32
41.73
55.97
69.93
65.58
62.84
52.50
41.29
29.80
0.41
1958
6.55
17.04
32.10
43.60
50.23
61.67
62.77
59.32
50.37
32.71
22.03
10.19
1959
6.45
27.89
8.58
30.93
53.71
64.17
59.84
63.55
53.43
35.48
26.73
-2.52
1960
13.52
21.79
17.87
24.97
55.77
61.40
66.68
58.19
49.50
35.48
20.80
25.97
1961
17.42
2.71
15.35
32.93
55.45
59.13
59.65
59.74
50.27
29.81
23.70
-3.42
1962
6.03
27.43
25.61
33.70
47.00
61.77
70.61
61.06
48.37
36.61
17.60
7.10
1963
22.65
16.04
23.48
31.43
51.74
57.23
64.26
57.55
57.13
31.19
5.20
19.94
1964
7.06
9.97
15.58
30.17
41.55
63.77
66.13
60.52
54.60
37.19
18.17
-1.45
1965
3.52
2.79
34.26
35.13
42.74
57.70
60.61
56.68
53.20
27.63
22.70
2.81
1966
4.32
17.64
7.03
34.10
42.00
63.43
60.94
57.74
53.07
29.74
20.73
2.55
1967
10.77
15.21
29.77
37.27
54.84
61.77
61.45
61.87
53.03
31.42
26.00
11.32
1968
10.74
9.28
22.77
33.57
51.71
63.10
68.84
63.19
49.47
33.00
20.57
1.42
1969
8.61
15.39
27.52
38.90
56.52
60.97
60.37
56.00
56.83
39.90
12.37
22.92
1970
M
M
16.50
25.00
M
M
M
M
M
M
M
-20.00
1971
M
M
M
M
M
M
M
M
M
M
M
M
1972
M
M
M
M
M
M
M
M
M
M
M
M
1973
26.50
M
M
M
M
M
M
M
M
M
12.50
5.04
1974
2.75
-0.71
13.00
40.68
56.75
62.50
M
M
47.71
29.69
8.64
0.47
1975
0.62
25.25
21.16
21.67
58.67
62.34
67.77
63.11
51.64
34.97
9.40
23.00
1976
26.50
31.75
35.00
42.93
50.86
59.36
66.24
63.92
51.70
33.90
22.33
6.71
1977
27.71
25.43
15.16
24.63
44.58
63.77
64.65
66.26
50.10
32.39
11.77
11.19
1978
25.42
19.43
26.39
42.89
55.77
54.87
65.00
65.53
53.23
33.94
29.57
27.32
1979
24.07
0.68
26.65
39.62
56.81
58.93
63.55
61.90
54.83
43.16
32.20
2.54
1980
25.07
22.55
31.61
43.41
53.52
56.87
64.19
61.00
45.29
39.37
24.71
0.58
1981
31.69
21.90
39.19
41.48
61.90
64.90
62.52
64.19
52.90
37.41
24.70
11.46
1982
14.41
17.93
28.52
30.39
50.49
60.96
63.39
64.26
54.21
29.47
23.76
13.94
1983
9.80
24.25
30.09
39.76
56.68
66.00
64.45
56.75
49.77
33.00
31.12
25.41
1984
9.27
-9.84
32.81
32.63
51.88
68.38
64.48
58.16
56.60
36.43
18.65
22.14
1985
31.64
7.74
23.45
22.28
47.06
59.77
67.58
78.00
49.88
32.07
27.35
33.15
1986
8.74
25.11
24.37
33.84
52.10
66.00
63.57
58.58
51.07
35.24
24.91
30.13
1987
18.67
22.04
31.25
37.72
51.90
61.87
65.71
66.32
51.37
41.59
18.70
9.71
1988
20.48
17.20
19.77
35.13
53.00
62.37
70.52
59.13
51.33
32.18
11.16
18.40
1989
-9.44
32.27
25.64
37.99
46.71
61.70
63.03
60.48
53.00
35.66
13.63
62.64
1990
100.00
100.00
53.74
43.14
52.20
60.66
67.84
62.74
48.15
33.09
21.21
19.93
1991
23.37
17.88
26.76
41.07
50.29
62.30
62.42
59.04
54.83
38.30
19.14
8.18
1992
17.92
12.25
24.88
32.80
41.51
61.42
65.67
58.02
39.95
30.20
22.95
13.36
1993
18.48
26.57
30.72
41.70
55.83
62.76
67.11
59.49
49.58
39.43
27.05
20.34
1994
11.68
13.47
19.63
38.42
53.96
61.28
62.81
58.83
50.86
30.49
24.46
16.91
1995
19.77
19.70
18.14
41.91
56.00
60.86
65.10
57.95
56.02
35.71
12.97
12.17
1996
7.07
13.29
34.22
36.94
54.90
59.98
62.48
57.43
47.00
29.36
24.56
6.74
1997
7.38
27.05
18.01
44.30
57.72
65.36
68.64
60.86
54.26
27.88
26.66
4.48
1998
3.91
12.02
34.49
40.10
48.32
60.80
64.69
55.23
50.72
36.53
22.52
4.88
1999
2.04
5.51
19.69
35.48
48.84
61.94
62.43
60.34
53.36
29.33
14.36
-7.08
2000
4.30
33.80
29.21
38.66
48.66
63.98
61.21
56.74
48.74
35.25
28.58
30.55
2001
24.57
28.53
23.17
38.30
47.15
64.70
60.92
60.74
53.42
29.45
14.36
0.94
2002
17.19
20.49
29.50
36.44
52.43
65.78
65.04
61.85
52.46
42.97
32.48
20.62
2003
16.79
29.49
22.19
41.66
51.74
64.76
64.75
63.01
52.40
40.42
29.00
9.30
2004
5.00
22.26
21.14
42.62
57.61
67.28
70.03
66.93
49.76
41.70
29.90
18.65
2005
14.36
20.81
28.28
38.89
59.52
66.38
68.29
64.52
52.52
35.54
8.42
19.92
2006
-5.51
27.37
20.45
32.06
54.01
60.68
65.21
58.36
55.34
43.09
19.82
11.80
2007
23.45
22.87
11.62
46.46
54.65
59.72
64.05
63.77
53.60
35.31
32.42
16.32
2008
8.43
6.37
22.30
32.06
51.63
59.60
61.21
61.67
53.30
25.50
11.90
18.76
2009
6.25
21.49
18.93
34.82
55.95
60.72
67.34
59.25
53.76
39.49
12.17
20.59
2010
6.24
20.36
14.93
36.20
57.32
62.48
61.32
59.35
56.06
37.34
23.06
6.63
2011
17.60
19.34
23.75
36.20
56.15
59.96
59.81
57.84
53.66
37.05
10.46
18.18
2012
-13.06
23.43
15.05
40.52
51.63
62.42
59.70
59.81
49.28
35.43
12.74
6.34
2013
20.84
13.04
23.70
29.96
49.25
67.82
68.07
60.92
49.94
44.48
25.76
17.89
2014
32.23
20.81
24.39
45.20
56.21
61.16
64.40
63.53
54.92
34.37
31.34
23.17
2015
12.89
22.36
29.45
41.12
56.56
67.22
63.82
59.12
49.22
42.28
29.78
17.37
2016
26.89
28.83
27.30
51.32
59.36
64.91
65.56
64.69
54.74
44.14
15.44
15.92
2017
10.17
12.78
15.92
43.52
55.46
63.98
68.55
60.49
51.70
40.62
27.35
31.34
2018
14.40
28.04
31.73
40.87
51.18
64.61
66.16
59.21
57.45
46.04
28.20
13.91
2019
17.81
32.87
37.69
40.49
56.01
69.84
69.98
63.31
53.98
41.30
26.06
11.32
2020
-3.13
15.18
24.97
42.41
59.65
62.17
63.55
64.65
52.22
40.55
27.55
17.70
2021
13.51
14.60
23.80
38.48
57.51
61.03
62.14
59.37
49.42
35.21
3.49
20.96
2022
4.74
16.53
29.80
39.96
56.03
68.45
62.25
58.46
52.34
38.36
25.30
13.65
2023
14.84
16.73
26.69
28.98
49.19
59.65
62.40
61.34
49.49
38.34
29.02
9.23
2024
14.26
25.36
25.18
38.70
49.59
65.19
62.54
57.61
52.63
37.50
21.31
22.10
2025
24.20
23.84
24.88
38.49
54.50
62.30
63.74
62.39
51.77
40.26
25.01
6.41
2026
-0.86
17.96
13.90
38.60
50.48
66.33
63.06
65.51
M
M
M
M
NCEI Climatology
12.70
20.13
21.99
36.90
52.00
62.10
63.60
60.50
52.71
37.91
24.31
16.30
Average Daily Low Temperature [F]
Year
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
1948
M
M
M
M
M
M
45.23
40.77
32.53
21.21
-0.97
-9.95
1949
-3.86
-8.02
13.25
10.45
26.40
40.70
47.10
46.71
41.93
27.29
20.07
-6.72
1950
-2.13
-17.28
12.06
21.10
31.84
41.23
47.55
47.35
38.53
23.52
4.17
-3.90
1951
-16.03
-1.46
-11.03
22.87
36.90
43.87
47.71
49.00
37.57
22.23
15.33
-2.52
1952
-13.00
-1.79
3.03
13.10
28.29
43.20
47.61
44.87
35.83
29.23
22.27
-6.65
1953
-12.77
-2.14
-8.19
21.97
36.03
45.20
47.65
48.29
36.13
20.42
7.87
-1.55
1954
-18.62
-22.75
2.97
20.87
36.61
41.50
45.58
46.81
38.07
29.55
14.13
-19.18
1955
13.31
-12.50
4.29
9.53
33.65
39.90
47.10
44.48
38.00
18.84
-2.60
-8.48
1956
-18.00
-13.90
-3.29
15.40
36.32
43.67
49.10
48.19
36.33
15.94
-9.90
-18.58
1957
8.52
-3.43
11.58
28.60
37.03
47.63
45.61
48.48
36.77
31.00
19.43
-9.72
1958
-8.52
4.68
17.84
25.03
32.16
45.03
48.06
45.65
36.53
19.39
6.10
-4.10
1959
-12.55
14.43
-19.29
11.40
35.52
44.40
44.74
45.42
34.87
18.29
12.73
-18.32
1960
0.94
4.90
0.32
2.83
38.03
41.37
48.65
42.97
35.97
24.32
7.17
10.29
1961
2.48
-16.50
-7.71
14.97
35.32
42.47
45.23
44.13
39.70
18.61
7.03
-20.06
1962
-14.03
14.07
6.65
18.90
33.32
44.10
51.65
47.55
35.47
26.68
5.40
-8.42
1963
11.48
3.14
3.94
12.93
36.03
42.20
48.16
45.55
40.70
20.52
-8.00
4.77
1964
-6.26
-9.69
-6.97
13.90
28.06
46.43
48.77
47.16
40.60
26.19
3.70
-17.29
1965
-7.06
-11.61
26.32
25.83
34.19
47.80
52.03
48.29
46.43
17.90
15.23
-6.77
1966
-3.06
5.50
-9.00
22.37
33.10
51.70
51.42
48.06
41.33
21.32
13.93
-8.87
1967
-1.94
3.00
15.55
30.07
42.29
51.97
51.90
51.61
40.47
22.81
16.23
1.13
1968
3.71
-1.38
4.23
23.10
39.90
51.43
56.55
51.45
35.80
24.03
10.80
-6.90
1969
0.68
5.54
15.97
27.70
43.16
46.50
48.20
42.29
38.17
30.87
3.60
14.08
1970
M
M
8.00
11.00
M
M
M
M
M
M
M
-20.00
1971
M
M
M
M
M
M
M
M
M
M
M
M
1972
M
M
M
M
M
M
M
M
M
M
M
M
1973
18.25
M
M
M
M
M
M
M
M
M
2.93
-1.80
1974
-4.29
-8.33
6.00
29.91
46.40
46.25
M
M
39.71
22.25
2.41
-4.47
1975
-6.33
15.25
2.76
5.67
52.33
48.90
54.46
52.56
40.80
27.10
2.07
18.33
1976
25.00
29.50
32.83
34.27
39.00
49.05
53.28
49.80
37.90
23.27
8.15
-4.71
1977
16.23
10.64
-4.16
7.07
31.61
44.40
49.00
49.87
41.00
20.35
-1.73
-2.68
1978
14.13
5.46
7.65
31.11
37.00
42.07
48.35
51.10
39.03
24.06
17.40
14.32
1979
12.21
-18.32
13.32
28.38
37.58
43.37
47.19
49.73
38.97
31.74
21.83
-11.79
1980
12.91
6.62
17.32
27.28
38.76
43.43
49.19
49.17
38.86
28.17
13.32
-13.88
1981
17.93
7.36
26.02
25.65
39.60
44.57
50.42
47.97
38.44
27.49
9.74
-5.82
1982
-1.53
-0.37
9.43
11.40
34.46
44.48
49.42
48.65
41.29
15.65
10.46
1.14
1983
9.20
12.81
12.74
23.99
39.62
46.03
50.03
43.38
35.88
26.52
24.48
18.59
1984
-5.73
-26.51
18.82
14.94
31.67
47.69
49.74
44.17
38.28
23.96
6.75
7.99
1985
20.54
-5.31
4.74
-0.50
32.25
41.97
49.74
54.00
40.96
23.92
15.93
21.47
1986
-1.62
10.97
3.98
16.48
34.19
47.90
50.60
46.26
42.22
23.37
14.82
20.01
1987
4.41
5.23
12.79
19.11
36.40
46.13
50.23
48.19
37.68
30.45
7.27
-6.83
1988
8.72
0.48
1.89
19.94
37.95
46.03
51.81
46.83
36.60
19.32
-1.33
4.67
1989
-26.86
20.25
6.98
27.16
34.65
44.87
49.75
49.10
44.41
26.85
-0.57
54.03
1990
100.00
84.67
39.80
27.51
40.98
47.31
53.36
50.52
39.79
26.12
10.36
10.02
1991
13.97
6.47
13.07
30.28
39.18
47.30
49.85
48.39
44.69
31.52
9.67
-3.79
1992
5.26
3.11
11.49
24.88
32.74
48.32
50.02
48.80
29.96
20.47
9.39
-1.44
1993
6.63
14.20
15.38
32.82
38.61
45.93
51.82
48.37
39.17
30.84
16.64
10.77
1994
0.28
2.05
3.18
23.31
37.09
43.71
50.09
47.24
38.55
17.40
9.92
2.55
1995
8.77
7.38
2.76
29.24
39.13
44.43
49.46
47.44
43.33
26.30
-0.46
0.82
1996
-2.34
0.07
17.69
19.96
36.54
42.83
48.55
44.54
32.06
15.67
12.14
-11.66
1997
-7.60
13.10
-1.74
25.28
35.48
45.08
49.07
49.77
41.12
10.46
15.67
-12.07
1998
-8.12
-0.67
23.55
25.82
35.66
44.48
49.83
43.55
39.68
26.37
12.32
-9.34
1999
-15.15
-13.19
-3.01
21.26
31.48
46.04
47.97
45.94
40.40
18.24
0.92
-24.32
2000
-10.21
20.27
15.45
21.44
33.10
43.94
47.56
44.95
35.24
22.88
19.10
16.55
2001
12.14
13.87
7.73
25.04
28.69
45.20
49.01
46.40
39.56
18.59
-0.94
-15.85
2002
3.78
6.22
12.08
20.90
37.01
46.46
48.49
46.11
40.34
31.71
21.14
10.28
2003
2.62
18.95
5.12
25.82
35.83
46.10
49.59
47.68
34.28
30.43
16.40
-7.77
2004
-9.71
4.94
2.62
26.30
41.23
48.32
53.31
51.47
34.82
31.83
19.16
5.93
2005
1.64
3.26
12.66
20.10
39.61
46.76
49.94
48.20
41.00
25.44
-6.70
5.64
2006
-17.94
12.65
1.05
16.16
36.30
44.72
50.17
44.48
40.70
33.10
4.58
-1.47
2007
8.68
6.29
-8.65
29.54
38.15
45.62
51.22
48.90
44.36
27.24
21.06
3.61
2008
-6.32
-12.69
7.21
16.28
35.19
44.96
46.57
42.97
40.40
13.42
-1.24
4.01
2009
-9.26
-0.07
1.46
19.45
36.87
44.17
49.59
44.46
37.37
29.77
-4.50
6.01
2010
-6.00
4.01
-5.74
20.72
36.12
44.90
48.14
48.20
39.56
26.25
11.36
-9.98
2011
1.69
-0.14
1.17
16.76
35.95
45.80
46.34
45.94
40.40
27.99
-5.26
4.54
2012
-28.94
6.61
-4.52
21.68
33.28
43.64
47.50
46.52
36.86
22.59
1.28
-10.85
2013
7.82
-3.23
2.97
11.42
29.68
48.20
51.44
49.30
38.06
34.21
12.86
6.16
2014
20.45
9.05
2.91
25.34
36.35
44.00
49.07
48.84
39.86
22.42
20.78
14.23
2015
-1.45
9.18
11.10
24.80
40.42
46.10
50.17
45.41
37.22
32.58
18.80
4.71
2016
16.21
14.19
14.06
32.30
41.36
47.43
51.51
51.34
39.08
29.50
3.62
2.50
2017
-4.46
-4.84
-7.83
27.92
36.95
48.48
52.48
47.72
40.28
31.11
16.62
17.89
2018
-0.25
11.44
17.64
27.20
36.65
43.95
50.80
48.37
43.39
36.28
16.23
-0.05
2019
5.24
22.67
25.37
25.37
40.52
49.07
53.75
50.15
42.87
28.53
15.40
-2.71
2020
-17.56
-4.71
5.39
27.52
40.01
46.16
51.46
47.78
38.03
30.93
15.88
5.50
2021
1.23
-0.10
2.75
20.87
38.84
47.43
50.72
46.54
37.15
26.18
-14.86
7.67
2022
-4.40
5.46
14.90
25.46
36.19
47.48
50.26
48.38
42.14
27.63
12.20
-0.73
2023
0.97
1.66
10.25
7.93
36.35
46.88
50.76
51.00
38.15
27.03
18.86
-4.43
2024
0.31
10.66
8.05
24.03
35.34
48.21
48.55
46.46
40.13
26.86
9.34
10.45
2025
9.85
9.47
8.98
24.40
37.15
45.79
51.45
49.77
37.49
31.47
15.67
-8.28
2026
-17.68
-4.00
-11.97
24.20
34.81
47.63
46.94
52.67
M
M
M
M
NCEI Climatology
0.90
6.50
7.00
21.21
34.10
44.50
49.01
47.31
39.41
26.40
12.80
3.71
Average Daily Temperature (high+low)/2 [F]
Year
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
1948
M
M
M
M
M
M
51.81
48.76
39.92
26.81
5.58
-1.91
1949
5.26
1.17
21.74
20.27
35.48
48.32
55.79
51.68
47.92
32.09
24.93
-0.37
1950
7.61
-8.68
21.15
28.73
40.68
49.80
56.73
55.48
45.77
30.60
12.28
3.65
1951
-8.27
8.96
-0.29
30.98
46.13
52.95
55.31
54.00
44.70
29.98
20.23
4.71
1952
-3.44
5.36
12.55
21.93
36.03
51.98
54.66
52.00
42.93
34.53
27.02
-0.02
1953
-5.31
6.25
4.31
32.07
45.58
55.17
59.21
53.81
44.33
26.95
14.82
5.26
1954
-9.53
-10.57
15.31
29.37
47.06
53.45
54.08
53.24
44.58
34.76
20.28
-11.55
1955
20.00
-3.25
15.11
18.83
41.77
47.10
54.66
51.50
44.33
24.92
5.93
0.50
1956
-9.00
-2.67
8.15
25.35
42.84
52.83
57.18
54.89
43.77
22.24
-1.12
-12.35
1957
16.50
5.50
19.95
35.17
46.50
58.78
55.60
55.66
44.63
36.15
24.62
-4.66
1958
-0.98
10.86
24.97
34.32
41.19
53.35
55.42
52.48
43.45
26.05
14.07
3.05
1959
-3.05
21.16
-5.35
21.17
44.61
54.28
52.29
54.48
44.15
26.89
19.73
-10.42
1960
7.23
13.34
9.10
13.90
46.90
51.38
57.66
50.58
42.73
29.90
13.98
18.13
1961
9.95
-6.89
3.82
23.95
45.39
50.80
52.44
51.94
44.98
24.21
15.37
-11.74
1962
-4.00
20.75
16.13
26.30
40.16
52.93
61.13
54.31
41.92
31.65
11.50
-0.66
1963
17.06
9.59
13.71
22.18
43.89
49.72
56.21
51.55
48.92
25.85
-1.40
12.35
1964
0.40
0.14
4.31
22.03
34.81
55.10
57.45
53.84
47.60
31.69
10.93
-9.37
1965
-1.77
-4.41
30.29
30.48
38.47
52.75
56.32
52.48
49.82
22.77
18.97
-1.98
1966
0.63
11.57
-0.98
28.23
37.55
57.57
56.18
52.90
47.20
25.53
17.33
-3.16
1967
4.42
9.11
22.66
33.67
48.56
56.87
56.68
56.74
46.75
27.11
21.12
6.23
1968
7.23
3.95
13.50
28.33
45.81
57.27
62.69
57.32
42.63
28.52
15.68
-2.74
1969
4.65
10.46
21.74
33.30
49.84
53.73
54.28
49.15
47.50
35.39
7.98
18.50
1970
M
M
12.25
18.00
M
M
M
M
M
M
M
-20.00
1971
M
M
M
M
M
M
M
M
M
M
M
M
1972
M
M
M
M
M
M
M
M
M
M
M
M
1973
22.38
M
M
M
M
M
M
M
M
M
7.71
1.62
1974
-0.77
-4.52
9.50
35.30
51.58
54.38
M
M
43.71
25.97
5.52
-2.00
1975
-2.85
20.25
11.96
13.67
55.50
55.62
61.12
57.83
46.22
31.03
5.73
20.67
1976
25.75
30.62
33.92
38.60
44.93
54.20
59.76
56.86
44.80
28.58
15.24
1.00
1977
21.97
18.04
5.50
15.85
38.10
54.08
56.82
58.06
45.55
26.37
5.02
4.26
1978
19.77
12.45
17.02
37.00
46.39
48.47
56.68
58.32
46.13
29.00
23.48
20.82
1979
18.14
-8.82
19.98
34.00
47.19
51.15
55.37
55.82
46.90
37.45
27.02
-4.62
1980
18.99
14.58
24.47
35.35
46.14
50.15
56.69
55.08
42.07
33.77
19.01
-6.65
1981
24.81
14.63
32.60
33.56
50.75
54.73
56.47
56.08
45.67
32.45
17.22
2.82
1982
6.44
8.78
18.98
20.89
42.48
52.72
56.40
56.45
47.75
22.56
17.11
7.54
1983
9.50
18.53
21.42
31.87
48.15
56.02
57.24
50.06
42.82
29.76
27.80
22.00
1984
1.77
-18.18
25.81
23.79
41.77
58.03
57.11
51.17
47.44
30.20
12.70
15.07
1985
26.09
1.22
14.09
10.89
39.66
50.87
58.66
66.00
45.42
27.99
21.64
27.31
1986
3.56
18.04
14.17
25.16
43.14
56.95
57.08
52.42
46.65
29.30
19.86
25.07
1987
11.54
13.64
22.02
28.42
44.15
54.00
57.97
57.26
44.52
36.02
12.99
1.44
1988
14.60
8.84
10.83
27.54
45.47
54.20
61.16
52.98
43.97
25.75
4.91
11.53
1989
-18.15
26.26
16.31
32.58
40.68
53.28
56.39
54.79
48.71
31.25
6.53
58.34
1990
100.00
92.34
46.77
35.33
46.59
53.98
60.60
56.63
43.97
29.61
15.79
14.97
1991
18.67
12.18
19.91
35.68
44.73
54.80
56.13
53.71
49.76
34.91
14.40
2.20
1992
11.59
7.68
18.18
28.84
37.13
54.87
57.85
53.41
34.96
25.33
16.17
5.96
1993
12.56
20.38
23.05
37.26
47.22
54.34
59.47
53.93
44.38
35.14
21.85
15.56
1994
5.98
7.76
11.40
30.86
45.52
52.50
56.45
53.04
44.70
23.94
17.19
9.73
1995
14.27
13.54
10.45
35.57
47.57
52.65
57.28
52.70
49.68
31.00
6.26
6.49
1996
2.36
6.68
25.95
28.45
45.72
51.41
55.52
50.99
39.53
22.52
18.35
-2.46
1997
-0.11
20.08
8.14
34.79
46.60
55.22
58.85
55.31
47.69
19.17
21.17
-3.80
1998
-2.10
5.68
29.02
32.96
41.99
52.64
57.26
49.39
45.20
31.45
17.42
-2.23
1999
-6.55
-3.84
8.34
28.37
40.16
53.99
55.20
53.14
46.88
23.78
7.64
-15.70
2000
-2.95
27.03
22.33
30.05
40.88
53.96
54.38
50.84
41.99
29.07
23.84
23.55
2001
18.35
21.20
15.45
31.67
37.92
54.95
54.96
53.57
46.49
24.02
6.71
-7.45
2002
10.49
13.36
20.79
28.67
44.72
56.12
56.76
53.98
46.40
37.34
26.81
15.45
2003
9.70
24.22
13.65
33.74
43.79
55.43
57.17
55.34
43.34
35.43
22.70
0.76
2004
-2.36
13.60
11.88
34.46
49.42
57.80
61.67
59.20
42.29
36.76
24.53
12.29
2005
8.00
12.04
20.47
29.50
49.56
56.57
59.12
56.36
46.76
30.49
0.86
12.78
2006
-11.72
20.01
10.75
24.11
45.15
52.70
57.69
51.42
48.02
38.10
12.20
5.17
2007
16.06
14.58
1.49
38.00
46.40
52.67
57.64
56.34
48.98
31.27
26.74
9.96
2008
1.05
-3.16
14.75
24.17
43.41
52.28
53.89
52.32
46.85
19.46
5.33
11.39
2009
-1.51
10.71
10.19
27.14
46.41
52.45
58.46
51.86
45.57
34.63
3.84
13.30
2010
0.12
12.19
4.59
28.46
46.72
53.69
54.73
53.77
47.81
31.80
17.21
-1.68
2011
9.65
9.60
12.46
26.48
46.05
52.88
53.08
51.89
47.03
32.52
2.60
11.36
2012
-21.00
15.02
5.26
31.10
42.45
53.03
53.60
53.16
43.07
29.01
7.01
-2.26
2013
14.33
4.90
13.33
20.69
39.46
58.01
59.76
55.11
44.00
39.35
19.31
12.03
2014
26.34
14.93
13.65
35.27
46.28
52.58
56.74
56.18
47.39
28.39
26.06
18.70
2015
5.72
15.77
20.27
32.96
48.49
56.66
57.00
52.26
43.22
37.43
24.29
11.04
2016
21.55
21.51
20.68
41.81
50.36
56.17
58.54
58.01
46.91
36.82
9.53
9.21
2017
2.85
3.97
4.04
35.72
46.21
56.23
60.51
54.11
45.99
35.87
21.98
24.61
2018
7.07
19.74
24.68
34.04
43.92
54.28
58.48
53.79
50.42
41.16
22.22
6.93
2019
11.52
27.77
31.53
32.93
48.26
59.45
61.87
56.73
48.43
34.91
20.73
4.31
2020
-10.35
5.24
15.18
34.96
49.83
54.16
57.51
56.21
45.12
35.74
21.71
11.60
2021
7.37
7.25
13.28
29.68
48.17
54.23
56.43
52.95
43.28
30.70
-5.69
14.32
2022
0.17
11.00
22.35
32.71
46.11
57.96
56.26
53.42
47.24
32.99
18.75
6.46
2023
7.91
9.19
18.47
18.46
42.77
53.26
56.58
56.17
43.82
32.68
23.94
2.40
2024
7.29
18.01
16.62
31.37
42.46
56.70
55.54
52.04
46.38
32.18
15.33
16.27
2025
17.03
16.65
16.93
31.44
45.83
54.05
57.60
56.08
44.63
35.86
20.34
-0.93
2026
-9.27
6.98
0.97
31.40
42.65
56.98
55.00
59.09
M
M
M
M
NCEI Climatology
6.80
13.32
14.50
29.06
43.05
53.30
56.30
53.90
46.06
32.15
18.56
10.00
Average Relative Humidity [%]
This value is computed via a simple average of available observations weighted
by the duration between observations.
