Frost history / Missoula 6 Nw Wfo, MT
Missoula 6 Nw Wfo, MT: frost dates by year
Last spring and first fall frost at NOAA station USC00245740, 1951 to 2025, measured from daily minimum temperatures.
Elevation 3,197 ft, 46.924, -114.091. Download the data (JSON), NOAA daily records
Summary at 32°F
| Last spring frost | First fall frost | |
|---|---|---|
| Median | May 13 | Sep 25 |
| Earliest | Apr 17 (2016) | Sep 3 (1958) |
| Latest | Jun 28 (1965) | Oct 25 (2023) |
| Trend | 3.4 days earlier per decade | 3.6 days later per decade |
| Years with data | 39 | 38 |
At 28°F (hard freeze) the median last spring date is Apr 30 and the median first fall date is Oct 11.
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 6 | Oct 6 | Apr 23 | Oct 15 |
| 2024 | May 4 | Oct 1 | Apr 28 | Oct 24 |
| 2023 | Apr 28 | Oct 25 | Apr 23 | Oct 25 |
| 2022 | May 12 | Oct 16 | May 9 | Oct 28 |
| 2021 | May 10 | Oct 8 | Apr 21 | Oct 11 |
| 2020 | May 5 | Oct 21 | Apr 17 | Oct 22 |
| 2019 | May 1 | Sep 29 | May 1 | Oct 1 |
| 2018 | Apr 24 | Oct 8 | Apr 24 | Oct 15 |
| 2017 | May 17 | no data | Apr 16 | no data |
| 2016 | Apr 17 | Sep 13 | Mar 30 | Oct 12 |
| 2015 | Apr 23 | Oct 21 | Apr 16 | Oct 28 |
| 2014 | May 13 | Sep 12 | May 12 | Sep 12 |
| 2013 | May 2 | Sep 27 | May 2 | Oct 4 |
| 2012 | May 13 | Oct 4 | May 11 | Oct 5 |
| 2011 | May 2 | Oct 9 | Apr 24 | Oct 18 |
| 2010 | May 21 | Oct 12 | May 7 | Oct 16 |
| 2009 | May 21 | Oct 5 | May 1 | Oct 6 |
| 2008 | May 13 | Sep 23 | May 1 | Oct 9 |
| 2007 | May 6 | Sep 30 | Apr 21 | Oct 26 |
| 2006 | May 10 | Sep 18 | May 10 | Oct 10 |
| 2005 | Apr 30 | Oct 9 | Apr 29 | Oct 10 |
| 2004 | May 14 | Oct 10 | Apr 29 | Oct 11 |
| 2003 | May 20 | Oct 11 | Apr 19 | Oct 11 |
| 2002 | no data | Sep 22 | no data | Oct 2 |
| 1966 | May 23 | no data | May 18 | no data |
| 1965 | Jun 28 | Sep 15 | May 18 | Sep 17 |
| 1964 | May 26 | Sep 10 | May 26 | Sep 12 |
| 1963 | May 13 | Sep 15 | Apr 25 | Oct 20 |
| 1962 | May 15 | Sep 12 | Apr 30 | Oct 7 |
| 1961 | May 12 | Sep 13 | Apr 26 | Sep 14 |
| 1960 | Jun 18 | Sep 8 | May 23 | Sep 22 |
| 1959 | May 27 | Sep 9 | May 12 | Oct 1 |
| 1958 | Apr 30 | Sep 3 | Apr 29 | Oct 17 |
| 1957 | Apr 27 | Sep 19 | Apr 18 | Oct 16 |
| 1956 | May 6 | Sep 6 | Apr 30 | Sep 22 |
| 1955 | May 31 | Sep 18 | May 28 | Sep 25 |
| 1954 | Jun 17 | Sep 4 | May 2 | Oct 1 |
| 1953 | May 25 | Sep 21 | May 3 | Oct 3 |
| 1952 | Jun 13 | Oct 6 | Apr 29 | Oct 14 |
| 1951 | Jun 2 | Sep 21 | May 29 | Oct 16 |
"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.