Rigby, ID: frost dates by year

Last spring and first fall frost at NOAA station USC00107689, 2008 to 2025, measured from daily minimum temperatures.

Elevation 4,856 ft, 43.676, -111.912. Download the data (JSON), NOAA daily records

Summary at 32°F

	Last spring frost	First fall frost
Median	May 16	Oct 5
Earliest	Apr 22 (2025)	Sep 9 (2020)
Latest	Jun 21 (2019)	Oct 27 (2015)
Trend	5.1 days earlier per decade	4.0 days later per decade
Years with data	16	17

At 28°F (hard freeze) the median last spring date is May 2 and the median first fall date is Oct 12.

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 22	no data	Apr 19	no data
2024	May 23	Oct 19	May 2	Oct 30
2023	Apr 28	Oct 26	Apr 23	Oct 26
2022	May 23	Oct 23	May 11	Oct 24
2021	May 10	Sep 29	May 9	Oct 12
2020	May 23	Sep 9	May 7	Oct 15
2019	Jun 21	Sep 30	May 3	Oct 6
2018	May 3	Sep 25	Apr 18	Oct 14
2017	May 18	Sep 23	Apr 22	Oct 9
2016	May 11	Oct 6	May 11	Oct 12
2015	May 10	Oct 27	Apr 15	Nov 6
2014	May 13	Sep 12	Apr 30	Sep 12
2013	May 2	Oct 5	May 2	Oct 5
2012	May 24	Oct 4	May 7	Oct 4
2011	May 18	Oct 6	May 1	Oct 26
2010	May 23	Oct 12	May 23	Oct 27
2009	no data	Oct 1	no data	Oct 6
2008	no data	Oct 9	no data	Oct 10

"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.