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 |
Copyright 2007 Illinois State Water Survey
Last Modified: September 11, 2007