Frost history / Challis Ap, ID
Challis Ap, ID: frost dates by year
Last spring and first fall frost at NOAA station USW00004114, 1999 to 2024, measured from daily minimum temperatures.
Elevation 5,033 ft, 44.523, -114.215. Download the data (JSON), NOAA daily records
Summary at 32°F
| Last spring frost | First fall frost | |
|---|---|---|
| Median | May 29 | Sep 18 |
| Earliest | May 3 (2018) | Sep 2 (2008) |
| Latest | Jun 19 (2024) | Oct 16 (2015) |
| Trend | 4.6 days earlier per decade | 5.7 days later per decade |
| Years with data | 25 | 26 |
At 28°F (hard freeze) the median last spring date is May 6 and the median first fall date is Oct 3.
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 | Jun 19 | Oct 1 | May 2 | Oct 19 |
| 2023 | May 10 | Sep 28 | Apr 23 | Oct 27 |
| 2022 | May 23 | Oct 10 | May 10 | Oct 16 |
| 2021 | Jun 11 | Sep 17 | May 9 | Sep 29 |
| 2020 | no data | Sep 9 | no data | Oct 22 |
| 2019 | May 10 | Sep 28 | May 3 | Oct 1 |
| 2018 | May 3 | Sep 25 | Apr 18 | Sep 25 |
| 2017 | Jun 11 | Sep 24 | May 14 | Oct 3 |
| 2016 | May 24 | Sep 13 | May 11 | Sep 13 |
| 2015 | May 10 | Oct 16 | Apr 17 | Oct 23 |
| 2014 | May 13 | Sep 12 | May 13 | Oct 17 |
| 2013 | May 24 | Sep 19 | May 2 | Oct 5 |
| 2012 | Jun 11 | Sep 12 | May 7 | Oct 4 |
| 2011 | Jun 10 | Oct 9 | May 2 | Oct 17 |
| 2010 | May 23 | Sep 6 | May 21 | Oct 12 |
| 2009 | May 21 | Sep 21 | May 13 | Oct 2 |
| 2008 | Jun 11 | Sep 2 | May 13 | Oct 9 |
| 2007 | May 29 | Sep 10 | May 6 | Sep 30 |
| 2006 | May 30 | Sep 17 | May 3 | Sep 17 |
| 2005 | May 25 | Sep 11 | Apr 30 | Sep 11 |
| 2004 | May 29 | Sep 21 | Apr 30 | Oct 11 |
| 2003 | May 20 | Sep 13 | May 20 | Sep 13 |
| 2002 | Jun 8 | Sep 8 | May 10 | Oct 1 |
| 2001 | Jun 14 | Sep 8 | May 6 | Oct 5 |
| 2000 | Jun 1 | Sep 23 | Apr 30 | Sep 23 |
| 1999 | Jun 9 | Sep 26 | May 11 | Sep 27 |
"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.