Frost history / Mason City 4SE, IL
Mason City 4SE, IL: frost dates by year
Last spring and first fall frost at NOAA station USC00115413, 1962 to 2010, measured from daily minimum temperatures.
Elevation 600 ft, 40.164, -89.651. Download the data (JSON), NOAA daily records
Summary at 32°F
| Last spring frost | First fall frost | |
|---|---|---|
| Median | Apr 21 | Oct 11 |
| Earliest | Mar 29 (1999) | Sep 20 (1962) |
| Latest | May 9 (1983) | Nov 3 (1973) |
| Trend | 2.8 days earlier per decade | 0.8 days earlier per decade |
| Years with data | 37 | 39 |
At 28°F (hard freeze) the median last spring date is Apr 7 and the median first fall date is Oct 24.
The trend is a straight-line fit through the years with a freeze. A positive spring trend means the last frost now comes later. Short or patchy records give noisy trends.
Chart
Last spring frost (32°F)
First fall frost (32°F)
Dots are single years. The gray line is the median, the green line the fitted trend.
Year by year
| Year | Last spring 32°F | First fall 32°F | Last spring 28°F | First fall 28°F |
|---|---|---|---|---|
| 2010 | Mar 29 | no data | Mar 27 | no data |
| 2009 | Apr 15 | Oct 10 | Apr 7 | Nov 12 |
| 2008 | Apr 15 | no data | Apr 14 | no data |
| 2006 | no data | Oct 12 | no data | Oct 24 |
| 2000 | Apr 12 | Oct 7 | Apr 12 | Oct 7 |
| 1999 | Mar 29 | Oct 14 | Mar 27 | Oct 18 |
| 1998 | Apr 18 | Oct 22 | Apr 5 | Nov 7 |
| 1997 | Apr 28 | Oct 15 | Apr 17 | Oct 22 |
| 1996 | Apr 27 | Oct 11 | Apr 10 | Oct 19 |
| 1995 | Apr 25 | Sep 23 | Apr 5 | Sep 23 |
| 1994 | Apr 7 | Oct 25 | Apr 7 | Nov 11 |
| 1993 | Apr 21 | Oct 10 | Apr 5 | Oct 31 |
| 1992 | Apr 28 | Oct 17 | Apr 28 | Oct 17 |
| 1991 | Mar 31 | Sep 20 | Mar 30 | Oct 20 |
| 1990 | Apr 18 | Oct 11 | Apr 18 | Oct 26 |
| 1989 | Apr 13 | Sep 24 | Apr 13 | Nov 3 |
| 1988 | Apr 19 | Oct 5 | Mar 30 | Oct 12 |
| 1987 | Apr 9 | Oct 3 | Apr 6 | Oct 8 |
| 1986 | Apr 23 | Oct 14 | Apr 22 | Nov 10 |
| 1985 | Apr 9 | Oct 2 | Apr 9 | Nov 20 |
| 1984 | Apr 24 | Sep 30 | Mar 23 | Nov 2 |
| 1983 | May 9 | Sep 22 | Apr 20 | Nov 12 |
| 1982 | Apr 21 | Oct 21 | Apr 11 | Oct 21 |
| 1981 | Apr 6 | Oct 19 | Apr 6 | Oct 23 |
| 1980 | Apr 25 | Oct 5 | Mar 22 | Oct 5 |
| 1979 | Apr 10 | Oct 13 | Apr 6 | Oct 13 |
| 1978 | May 3 | Oct 8 | Mar 27 | Nov 21 |
| 1977 | Apr 29 | Oct 13 | Apr 5 | Nov 11 |
| 1976 | May 3 | Oct 16 | Apr 12 | Oct 17 |
| 1975 | Apr 15 | Oct 26 | Apr 7 | Nov 14 |
| 1974 | Apr 24 | Sep 23 | Apr 9 | Oct 2 |
| 1973 | Apr 13 | Nov 3 | Apr 13 | Nov 5 |
| 1972 | Apr 26 | Oct 15 | Apr 8 | Oct 19 |
| 1971 | Apr 22 | Oct 31 | Apr 3 | Nov 4 |
| 1970 | Apr 5 | Oct 10 | Apr 5 | Nov 1 |
| 1969 | no data | Oct 14 | no data | Oct 22 |
| 1968 | Apr 25 | no data | Apr 15 | no data |
| 1967 | Apr 24 | Oct 11 | Apr 24 | Oct 26 |
| 1966 | no data | Oct 6 | no data | Oct 25 |
| 1964 | no data | Oct 6 | no data | Oct 10 |
| 1963 | Apr 24 | Oct 29 | Apr 24 | Nov 2 |
| 1962 | no data | Sep 20 | no data | Oct 24 |
"none" means the station recorded no freeze at that threshold in that half of the year. "no data" means more than 10% of the season's daily readings were missing. Years with no usable data are left out. See the methodology for the rules, and the ZIP lookup for 1991 to 2020 frost probabilities.