Altona, IL: frost dates by year

Last spring and first fall frost at NOAA station USC00110140, 2006 to 2024, measured from daily minimum temperatures.

Elevation 765 ft, 41.120, -90.164. Download the data (JSON), NOAA daily records

Summary at 32°F

	Last spring frost	First fall frost
Median	Apr 24	Oct 12
Earliest	Apr 8 (2017)	Sep 24 (2012)
Latest	May 12 (2020)	Nov 1 (2021)
Trend	5.4 days later per decade	8.0 days later per decade
Years with data	16	13

At 28°F (hard freeze) the median last spring date is Apr 16 and the median first fall date is Oct 22.

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
2024	Apr 22	no data	Mar 28	no data
2023	Apr 27	Oct 30	Apr 25	Oct 30
2022	Apr 27	Oct 8	Apr 19	Oct 18
2021	Apr 22	Nov 1	Apr 22	Nov 2
2020	May 12	no data	May 10	no data
2019	Apr 29	Oct 12	Apr 16	Nov 1
2018	Apr 30	Oct 12	Apr 30	Oct 18
2017	Apr 8	Oct 29	Apr 8	Oct 29
2015	May 2	no data	Apr 24	no data
2014	Apr 24	Oct 20	Apr 16	Oct 30
2013	Apr 21	Oct 22	Apr 21	Oct 22
2012	Apr 24	Sep 24	Apr 13	Oct 6
2011	no data	Oct 3	no data	Oct 21
2010	Apr 10	no data	Mar 27	no data
2009	Apr 17	Oct 10	Apr 13	Oct 10
2008	no data	Oct 21	no data	Oct 27
2007	Apr 16	no data	Apr 15	no data
2006	Apr 27	Oct 11	Apr 10	Oct 11

"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.