Frost history / Pompeys Pillar 15N, MT
Pompeys Pillar 15N, MT: frost dates by year
Last spring and first fall frost at NOAA station USC00246647, 1999 to 2025, measured from daily minimum temperatures.
Elevation 3,390 ft, 46.197, -108.004. Download the data (JSON), NOAA daily records
Summary at 32°F
| Last spring frost | First fall frost | |
|---|---|---|
| Median | May 21 | Sep 29 |
| Earliest | Apr 22 (2007) | Aug 17 (2002) |
| Latest | Jun 11 (2008) | Oct 25 (2022) |
| Trend | 6.4 days earlier per decade | 5.5 days later per decade |
| Years with data | 23 | 26 |
At 28°F (hard freeze) the median last spring date is May 7 and the median first fall date is Oct 6.
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 26 | Oct 13 | Apr 20 | Oct 29 |
| 2024 | May 24 | Oct 19 | May 4 | Oct 30 |
| 2023 | Apr 23 | Oct 6 | Apr 22 | Oct 25 |
| 2022 | May 22 | Oct 25 | Apr 25 | Nov 3 |
| 2020 | no data | Sep 9 | no data | Oct 15 |
| 2019 | May 19 | Sep 30 | May 10 | Oct 1 |
| 2018 | Apr 28 | Sep 21 | Apr 26 | Sep 26 |
| 2017 | May 20 | Sep 17 | May 19 | Oct 4 |
| 2016 | May 14 | Oct 6 | May 14 | Oct 6 |
| 2015 | May 21 | Aug 23 | May 11 | Oct 16 |
| 2014 | Jun 7 | Sep 11 | May 9 | Sep 12 |
| 2013 | May 3 | Sep 28 | May 2 | Oct 5 |
| 2012 | May 26 | Oct 3 | May 11 | Oct 6 |
| 2011 | May 31 | Sep 21 | May 5 | Oct 26 |
| 2010 | May 23 | Oct 12 | May 8 | Oct 12 |
| 2009 | Jun 10 | Sep 28 | May 1 | Oct 6 |
| 2008 | Jun 11 | Oct 7 | May 3 | Oct 12 |
| 2007 | Apr 22 | Sep 30 | Apr 13 | Sep 30 |
| 2006 | May 11 | Oct 10 | May 5 | Oct 11 |
| 2005 | May 14 | Sep 28 | May 13 | Oct 6 |
| 2004 | no data | Sep 21 | no data | Sep 21 |
| 2003 | Jun 7 | Sep 18 | May 20 | Sep 18 |
| 2002 | May 24 | Aug 17 | May 9 | Oct 12 |
| 2001 | May 7 | Oct 5 | May 7 | Oct 5 |
| 2000 | Jun 1 | Sep 22 | May 13 | Sep 22 |
| 1999 | no data | Sep 29 | no data | Oct 3 |
"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.