Knox Wwtp, IN: frost dates by year

Last spring and first fall frost at NOAA station USC00124657, 2007 to 2025, measured from daily minimum temperatures.

Elevation 690 ft, 41.305, -86.629. Download the data (JSON), NOAA daily records

Summary at 32°F

	Last spring frost	First fall frost
Median	Apr 27	Oct 17
Earliest	Apr 15 (2016)	Oct 2 (2011)
Latest	May 12 (2021)	Oct 31 (2023)
Trend	2.5 days later per decade	3.8 days later per decade
Years with data	19	19

At 28°F (hard freeze) the median last spring date is Apr 17 and the median first fall date is Oct 31.

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 17	Oct 24	Apr 16	Nov 10
2024	Apr 27	Oct 17	Apr 6	Nov 22
2023	Apr 28	Oct 31	Apr 27	Oct 31
2022	Apr 27	Oct 8	Apr 27	Oct 18
2021	May 12	Oct 27	Apr 22	Nov 3
2020	May 12	Oct 16	May 9	Oct 31
2019	Apr 21	Oct 12	Apr 2	Nov 1
2018	Apr 30	Oct 17	Apr 29	Oct 18
2017	May 9	Oct 26	Apr 8	Nov 8
2016	Apr 15	Oct 25	Apr 12	Nov 12
2015	Apr 28	Oct 17	Apr 24	Oct 18
2014	Apr 20	Oct 22	Apr 17	Nov 1
2013	Apr 26	Oct 22	Apr 22	Oct 22
2012	Apr 29	Oct 6	Apr 27	Oct 8
2011	Apr 22	Oct 2	Apr 2	Oct 30
2010	Apr 28	Oct 5	Mar 31	Oct 22
2009	Apr 24	Oct 11	Apr 23	Nov 1
2008	May 1	Oct 22	Apr 16	Oct 29
2007	Apr 19	Oct 28	Apr 17	Nov 2

"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.