Historical Climate Data

Precipitation Summary

Station: 115413 MASON CITY, IL

1971-2000 NCDC Normals

Element Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann
Prec. (in) 1.56 1.53 2.77 3.34 4.20 3.70 4.04 3.47 3.00 2.73 2.95 2.42 35.71

Precipitation Extremes

Period of Record: 1937-2006


Month
High (in)
Year
Low (in)
Year 		1-Day
Max (in)
Date
Jan 5.58 1949 0.06 1986 2.57 01-02-1965
Feb 4.02 1990 0.10 2004 2.08 02-22-1990
Mar 8.17 1973 0.00 2001 2.77 03-11-1939
Apr 7.32 1970 0.51 1971 2.76 04-30-1970
May 11.81 1995 0.18 1964 3.89 05-17-1995
Jun 9.91 1998 0.49 1971 3.68 06-27-1951
Jul 11.45 1992 0.21 1988 4.10 07-29-2002
Aug 7.45 1965 0.45 1937 3.26 08-06-1991
Sep 10.38 1993 0.11 1979 4.87 09-14-1993
Oct 8.77 1991 0.02 1964 4.82 10-04-1991
Nov 9.44 1985 0.33 1999 4.81 11-05-2004
Dec 7.29 1982 0.35 1976 3.10 12-03-1982
             
Annual 56.56 1993 18.86 2005 4.87 09-14-1993
Winter 13.78 1950 1.60 2004 3.10 12-03-1982
Spring 18.82 1995 4.03 2005 3.89 05-17-1995
Summer 22.24 1993 4.97 1971 4.10 07-29-2002
Fall 16.23 1993 3.45 1999 4.87 09-14-1993

Precipitation Threshold Climatology

Derived from 1971-2000 Averages:

*Annual/seasonal totals may differ from the sum of the monthly totals due to rounding.


Month 		# Days
Total ≥ 0.01" 		# Days
Total ≥ 0.10" 		# Days
Total ≥ 0.50" 		# Days
Total ≥ 1.00"
Jan 7.7 4.0 0.8 0.2
Feb 7.2 3.9 0.8 0.2
Mar 9.7 6.0 1.8 0.6
Apr 10.5 7.0 2.2 0.5
May 11.0 7.2 2.5 1.1
Jun 9.8 6.6 2.5 1.1
Jul 8.7 6.2 2.7 1.3
Aug 8.0 5.7 2.4 1.0
Sep 7.3 5.3 2.0 0.9
Oct 9.0 5.2 1.8 0.4
Nov 9.1 6.4 2.1 0.6
Dec 8.3 5.1 1.5 0.5
         
Annual 106.3 68.6 23.0 8.2
Winter 23.1 13.0 3.1 0.9
Spring 31.2 20.2 6.5 2.1
Summer 26.5 18.5 7.5 3.4
Fall 25.4 16.9 5.9 1.8

Temperature Summary

Station 115413 MASON CITY, IL

1971-2000 NCDC Normals

Element Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann
High °F 33.1 39.2 52.0 65.1 75.6 84.3 87.4 85.3 79.5 67.3 51.0 37.6 63.1
Low °F 15.7 20.6 30.5 40.5 51.3 60.4 64.1 62.2 54.5 43.5 32.4 21.3 41.4
Mean °F 24.4 29.9 41.3 52.8 63.5 72.4 75.8 73.8 67.0 55.4 41.7 29.5 52.3
HDD 1259 983 736 375 150 11 0 10 59 312 698 1102 5695
CDD 0 0 0 8 101 232 333 281 118 15 0 0 1088

HDD - heating degree days (base 65F); CDD - cooling degree days (base 65F)

Temperature Extremes

Period of Record: 1962-2006


Month 		High
Mean °F
Year 		Low
Mean °F
Year 		1-Day
Max °F
Date 		1-Day
Min °F
Date
Jan 37.2 1990 10.2 1977 70 01-31-1989 -24 01-17-1977
Feb 40.1 1998 16.8 1978 75 02-26-1996 -21 02-03-1996
Mar 47.9 1973 29.8 1965 87 03-28-1985 -8 03-05-1978
Apr 59.4 2005 47.4 1983 91 04-25-1986 15 04-06-1982
May 70.5 1987 58.3 1967 96 05-25-1967 29 05-03-1976
Jun 77.8 2005 67.3 1982 103 06-25-1988 39 06-01-1993
Jul 79.8 1983 72.2 1967 104 07-25-2005 45 07-27-1962
Aug 80.1 1983 68.8 1992 103 08-20-1983 40 08-28-1986
Sep 71.7 1998 62.1 1974 99 09-01-1984 28 09-23-1995
Oct 65.2 1963 48.7 1976 94 10-04-2006 18 10-26-1962
Nov 48.4 1999 33.9 1976 82 11-01-2000 -5 11-30-1964
Dec 38.6 1982 16.2 1983 73 12-03-1970 -23 12-22-1989
                 
Annual 56.4 2006 50.1 1978 104 07-25-1905 -24 01-17-1977
Winter 34.5 1983 19.5 1978 75 02-26-1996 -24 01-17-1977
Spring 58.1 1977 48.3 1984 96 05-25-1967 -8 03-05-1978
Summer 77.8 1983 70.7 1992 104 07-25-1905 39 06-01-1993
Fall 58.9 1963 49.0 1976 99 09-01-1984 -5 11-30-1964

Temperature Threshold Climatology

Derived from 1971-2000 Averages:

*Annual/seasonal values may differ from the sum of the monthly values due to rounding.


Month 		# Days
High ≥ 90°F 		# Days
High ≤ 32°F 		# Days
Low ≤ 32°F 		# Days
Low ≤ 0°F
Jan 0.0 14.3 28.1 4.6
Feb 0.0 8.6 22.7 2.7
Mar 0.0 1.9 16.9 0.1
Apr 0.0 0.1 5.3 0.0
May 1.0 0.0 0.2 0.0
Jun 6.1 0.0 0.0 0.0
Jul 9.6 0.0 0.0 0.0
Aug 6.2 0.0 0.0 0.0
Sep 3.0 0.0 0.3 0.0
Oct 0.0 0.0 4.2 0.0
Nov 0.0 1.3 15.6 0.0
Dec 0.0 9.1 25.7 2.2
         
Annual 26.0 35.1 119.1 9.7
Winter 0.0 32.1 76.5 9.5
Spring 1.1 2.0 22.3 0.1
Summer 21.8 0.0 0.0 0.0
Fall 3.0 1.3 20.1 0.0

Snowfall Summary

Station: 115413 MASON CITY, IL

1971-2000 Averages

Element Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann
Snow (in) 6.1 4.8 2.4 0.6 0.0 0.0 0.0 0.0 0.0 0.0 1.3 5.1 20.3

Snowfall Extremes

Period of Record: 1937-2006

Month High (in) Year 1-Day Max (in) Date
Jan 18.4 1979 8.0 01-30-1939
Feb 15.0 1989 6.0 02-24-1975
Mar 13.0 1978 8.0 03-08-1999
Apr 8.0 1982 4.0 04-14-1980
May 0.0 - - -
Jun 0.0 - - -
Jul 0.0 - - -
Aug 0.0 - - -
Sep 0.0 - - -
Oct 0.2 1967 0.2 10-31-1993
Nov 8.0 1975 4.5 11-27-1975
Dec 20.0 1973 8.0 12-19-1973
Season (Jul-Jun) 45.5 1977-1978 8.0 12-19-1973

Snowfall Threshold Climatology

Derived from 1971-2000 Averages

*Annual values may differ from the sum of the monthly values due to rounding.


Month 		# Days
Total ≥ 0.1" 		# Days
Total ≥ 1.0" 		# Days
Total ≥ 2.0" 		# Days
Total ≥ 5.0"
Jan 3.2 2.1 1.1 0.1
Feb 3.2 2.1 1.1 0.1
Mar 1.8 1.0 0.5 0.1
Apr 0.4 0.2 0.2 0.0
May 0.0 0.0 0.0 0.0
Jun 0.0 0.0 0.0 0.0
Jul 0.0 0.0 0.0 0.0
Aug 0.0 0.0 0.0 0.0
Sep 0.0 0.0 0.0 0.0
Oct 0.0 0.0 0.0 0.0
Nov 0.8 0.6 0.3 0.0
Dec 3.5 2.2 1.2 0.1
Annual 14.5 8.6 4.7 0.4

Growing Season Summary

Station: 115413 MASON CITY, IL

Growing Degree Day Averages

Derived from 1971-2000 Data

Base Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ann
40 13 40 164 408 740 979 1108 1052 806 489 160 32 5995
45 4 15 92 280 585 830 955 898 657 345 91 14 4771
50 1 4 49 172 433 681 801 743 511 221 44 6 3670
55 0 0 23 92 292 531 648 588 369 125 18 2 2693
60 0 0 9 40 173 384 494 434 240 59 5 0 1842
50** 7 25 103 249 466 658 760 717 525 299 92 17 3922

**Modified Growing Degree Days: Base 50, Ceiling 86.

Growing Season Summary

Derived from 1971-2000 Averages

Date of Last Spring Occurrence Date of First Fall Occurrence
Temp °F Median Early 90% 10% Late Median Early 90% 10% Late
32 4/21 3/28 4/07 5/01 5/08 10/13 9/19 9/23 10/26 11/03
30 4/11 3/26 3/30 4/29 5/08 10/16 9/23 10/02 11/06 11/13
28 4/07 3/23 3/27 4/19 4/29 10/23 9/22 10/07 11/13 11/21
24 4/04 3/12 3/17 4/12 4/18 11/04 10/11 10/20 11/22 11/29
20 3/18 2/22 3/04 4/09 4/10 11/15 10/20 10/31 12/03 12/11
16 3/08 2/07 2/11 3/25 4/06 11/29 11/02 11/08 12/14 12/22

Length of Growing Season (Days)

Derived from 1971-2000 Averages

Temp °F Median Shortest 10% 90% Longest
32 173 136 155 198 204
30 183 152 167 214 221
28 201 171 177 223 239
24 217 190 192 243 255
20 248 194 217 264 270
16 268 223 233 295 306

Back to the Station List

Copyright 2007 Illinois State Water Survey
Jim Angel, State Climatologist, jimangel@illinois.edu
Last Modified: September 11, 2007