Frost history / Chinook 35SE, MT
Chinook 35SE, MT: frost dates by year
Last spring and first fall frost at NOAA station USC00241730, 2001 to 2024, measured from daily minimum temperatures.
Elevation 3,360 ft, 48.173, -109.005. Download the data (JSON), NOAA daily records
Summary at 32°F
| Last spring frost | First fall frost | |
|---|---|---|
| Median | May 23 | Sep 24 |
| Earliest | May 5 (2006) | Sep 8 (2020) |
| Latest | Jun 19 (2004) | Oct 17 (2022) |
| Trend | 3.5 days earlier per decade | 4.9 days later per decade |
| Years with data | 15 | 17 |
At 28°F (hard freeze) the median last spring date is May 13 and the median first fall date is Oct 5.
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 | no data | Oct 13 | no data | Oct 13 |
| 2022 | May 23 | Oct 17 | May 23 | Oct 25 |
| 2021 | May 23 | Sep 30 | May 22 | Oct 12 |
| 2020 | May 13 | Sep 8 | May 12 | Sep 9 |
| 2015 | May 30 | no data | May 19 | no data |
| 2014 | May 18 | Sep 10 | May 14 | Sep 12 |
| 2013 | no data | Oct 2 | no data | Oct 4 |
| 2012 | May 30 | Oct 3 | May 11 | Oct 5 |
| 2011 | no data | Sep 14 | no data | Oct 14 |
| 2010 | May 12 | Oct 13 | May 9 | Oct 16 |
| 2009 | Jun 8 | no data | May 13 | no data |
| 2008 | Jun 11 | Oct 7 | May 12 | Oct 9 |
| 2007 | May 8 | Sep 14 | May 6 | Oct 4 |
| 2006 | May 5 | Sep 17 | May 5 | Oct 8 |
| 2005 | May 30 | Sep 24 | May 15 | Sep 28 |
| 2004 | Jun 19 | Sep 21 | May 14 | Oct 1 |
| 2003 | May 20 | Sep 17 | May 9 | Sep 24 |
| 2002 | May 25 | Sep 22 | May 25 | Sep 22 |
| 2001 | no data | Oct 4 | no data | Oct 5 |
"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.