Frost history / Shelby, MT
Shelby, MT: frost dates by year
Last spring and first fall frost at NOAA station USC00247500, 1951 to 2025, measured from daily minimum temperatures.
Elevation 3,325 ft, 48.513, -111.855. Download the data (JSON), NOAA daily records
Summary at 32°F
| Last spring frost | First fall frost | |
|---|---|---|
| Median | May 22 | Sep 20 |
| Earliest | Apr 28 (2023) | Aug 28 (2018) |
| Latest | Jun 22 (2015) | Oct 6 (2025) |
| Trend | 0.9 days earlier per decade | 0.9 days later per decade |
| Years with data | 35 | 35 |
At 28°F (hard freeze) the median last spring date is May 11 and the median first fall date is Sep 28.
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 | May 22 | Oct 6 | May 6 | Oct 6 |
| 2024 | May 3 | Sep 21 | Apr 21 | Oct 3 |
| 2023 | Apr 28 | Oct 6 | Apr 28 | Oct 24 |
| 2022 | May 22 | Sep 21 | May 22 | Sep 21 |
| 2021 | May 24 | Oct 2 | May 22 | Oct 8 |
| 2020 | May 5 | Oct 1 | May 5 | Oct 15 |
| 2019 | May 19 | Sep 27 | May 9 | Sep 29 |
| 2018 | May 12 | Aug 28 | Apr 26 | Sep 30 |
| 2017 | May 18 | Sep 17 | May 8 | Sep 21 |
| 2016 | May 15 | Sep 13 | May 11 | Sep 13 |
| 2015 | Jun 22 | Sep 7 | May 9 | Sep 28 |
| 2014 | May 14 | Sep 9 | May 13 | Sep 12 |
| 2013 | May 8 | Sep 20 | May 2 | Sep 27 |
| 2012 | May 29 | Sep 12 | May 12 | Oct 5 |
| 2011 | May 31 | Sep 20 | May 10 | Sep 29 |
| 2010 | May 13 | Sep 7 | May 13 | Oct 14 |
| 2009 | Jun 8 | Sep 28 | May 2 | Oct 2 |
| 2008 | Jun 11 | Sep 2 | May 13 | Oct 9 |
| 2007 | May 26 | Sep 13 | Apr 21 | Sep 13 |
| 2006 | May 14 | Sep 2 | May 5 | Sep 18 |
| 2005 | May 30 | Sep 24 | May 10 | Sep 24 |
| 2004 | Jun 18 | Sep 21 | May 13 | Sep 21 |
| 2003 | May 20 | Sep 17 | May 20 | Sep 18 |
| 2002 | May 23 | Sep 8 | May 16 | Sep 8 |
| 2001 | May 21 | Oct 2 | May 21 | Oct 5 |
| 2000 | Jun 13 | Sep 20 | May 15 | Sep 21 |
| 1999 | May 13 | Sep 12 | May 11 | Sep 27 |
| 1998 | Jun 3 | Sep 21 | Apr 21 | Oct 4 |
| 1997 | May 19 | Sep 19 | May 19 | Sep 19 |
| 1996 | no data | Sep 23 | no data | Sep 24 |
| 1995 | no data | Sep 20 | no data | Sep 20 |
| 1956 | May 13 | no data | May 13 | no data |
| 1955 | May 31 | Sep 10 | May 28 | Sep 18 |
| 1954 | May 14 | Sep 21 | May 3 | Sep 30 |
| 1953 | May 23 | Sep 21 | May 17 | Oct 4 |
| 1952 | May 31 | Sep 8 | Apr 21 | Oct 2 |
| 1951 | Jun 1 | no data | May 29 | no data |
"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.