Frost history / Lewistown 11 Sse, MT
Lewistown 11 Sse, MT: frost dates by year
Last spring and first fall frost at NOAA station USC00244978, 1951 to 2025, measured from daily minimum temperatures.
Elevation 4,965 ft, 46.906, -109.411. Download the data (JSON), NOAA daily records
Summary at 32°F
| Last spring frost | First fall frost | |
|---|---|---|
| Median | May 30 | Sep 15 |
| Earliest | May 2 (2018) | Aug 28 (2018) |
| Latest | Jul 4 (2023) | Oct 3 (1952) |
| Trend | 2.0 days later per decade | 1.2 days earlier per decade |
| Years with data | 20 | 19 |
At 28°F (hard freeze) the median last spring date is May 10 and the median first fall date is Sep 29.
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 | Jun 23 | Sep 4 | May 7 | Oct 6 |
| 2024 | Jun 19 | Sep 21 | May 22 | Oct 19 |
| 2023 | Jul 4 | Sep 20 | Apr 28 | Oct 14 |
| 2022 | May 23 | Sep 9 | May 22 | Oct 7 |
| 2021 | no data | Sep 2 | no data | Sep 21 |
| 2020 | May 14 | Sep 7 | May 8 | Sep 7 |
| 2019 | Jun 19 | Sep 27 | May 19 | Sep 29 |
| 2018 | May 2 | Aug 28 | Apr 24 | Sep 29 |
| 2017 | no data | Sep 15 | no data | Sep 25 |
| 2016 | May 31 | Sep 12 | May 14 | Sep 13 |
| 2015 | May 21 | no data | May 10 | no data |
| 2014 | Jun 12 | Sep 10 | May 13 | Sep 11 |
| 2013 | Jun 5 | Sep 26 | May 3 | Oct 4 |
| 2012 | May 30 | no data | May 19 | no data |
| 2011 | Jun 10 | no data | May 19 | no data |
| 1957 | May 24 | Sep 18 | Apr 27 | Sep 18 |
| 1956 | May 13 | Sep 3 | May 3 | Sep 5 |
| 1955 | May 27 | Sep 21 | May 9 | Sep 22 |
| 1954 | May 31 | Sep 28 | May 3 | Oct 1 |
| 1953 | May 23 | Sep 21 | May 14 | Oct 3 |
| 1952 | May 10 | Oct 3 | Apr 22 | Oct 5 |
| 1951 | Jun 6 | Sep 15 | May 29 | Sep 15 |
"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.