Knoxville, IL: frost dates by year

Last spring and first fall frost at NOAA station USC00114780, 2006 to 2025, measured from daily minimum temperatures.

Elevation 728 ft, 40.903, -90.290. Download the data (JSON), NOAA daily records

Summary at 32°F

	Last spring frost	First fall frost
Median	Apr 22	Oct 19
Earliest	Apr 7 (2017)	Oct 6 (2012)
Latest	May 9 (2020)	Nov 12 (2016)
Trend	1.5 days later per decade	2.1 days earlier per decade
Years with data	20	20

At 28°F (hard freeze) the median last spring date is Apr 13 and the median first fall date is Oct 29.

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
2025	Apr 16	Oct 23	Apr 8	Nov 2
2024	Apr 21	Oct 16	Apr 6	Oct 16
2023	Apr 26	Oct 10	Apr 24	Oct 30
2022	Apr 27	Oct 8	Apr 19	Oct 18
2021	Apr 22	Nov 2	Apr 22	Nov 2
2020	May 9	Oct 16	May 9	Oct 28
2019	Apr 29	Oct 12	Apr 15	Oct 31
2018	Apr 29	Oct 12	Apr 20	Oct 21
2017	Apr 7	Oct 29	Mar 22	Oct 29
2016	Apr 13	Nov 12	Apr 12	Nov 12
2015	Apr 23	Oct 17	Apr 4	Nov 8
2014	Apr 18	Oct 30	Apr 16	Nov 1
2013	Apr 21	Oct 22	Apr 5	Oct 25
2012	Apr 23	Oct 6	Apr 12	Oct 28
2011	May 5	Oct 21	May 4	Oct 28
2010	Apr 10	Oct 29	Mar 27	Oct 29
2009	Apr 16	Oct 10	Apr 9	Nov 3
2008	Apr 29	Oct 28	Apr 14	Oct 28
2007	Apr 16	Oct 28	Apr 15	Nov 2
2006	Apr 26	Oct 12	Mar 26	Oct 23

"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.