Frost history / St Mary, MT
St Mary, MT: frost dates by year
Last spring and first fall frost at NOAA station USC00247292, 1981 to 2015, measured from daily minimum temperatures.
Elevation 4,560 ft, 48.739, -113.429. Download the data (JSON), NOAA daily records
Summary at 32°F
| Last spring frost | First fall frost | |
|---|---|---|
| Median | Jun 5 | Sep 10 |
| Earliest | May 21 (1988) | Aug 10 (1997) |
| Latest | Jul 17 (1999) | Sep 26 (2013) |
| Trend | 1.0 days later per decade | 2.8 days earlier per decade |
| Years with data | 24 | 25 |
At 28°F (hard freeze) the median last spring date is May 18 and the median first fall date is Sep 22.
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 |
|---|---|---|---|---|
| 2015 | May 22 | no data | May 19 | no data |
| 2014 | no data | Sep 4 | no data | Sep 9 |
| 2013 | Jun 3 | Sep 26 | May 5 | Sep 26 |
| 2012 | May 27 | Aug 15 | May 19 | Sep 11 |
| 2011 | no data | Sep 2 | no data | Sep 28 |
| 2010 | Jun 18 | Sep 1 | May 23 | Oct 15 |
| 2004 | Jun 20 | Sep 10 | May 17 | Oct 1 |
| 2002 | Jun 14 | no data | May 23 | no data |
| 2001 | Jun 19 | Sep 9 | May 20 | Oct 5 |
| 2000 | Jun 2 | Sep 11 | May 8 | Sep 21 |
| 1999 | Jul 17 | no data | May 11 | no data |
| 1997 | Jun 28 | Aug 10 | May 8 | Sep 19 |
| 1996 | May 26 | Sep 22 | May 21 | Sep 23 |
| 1995 | Jun 28 | Sep 18 | May 27 | Sep 21 |
| 1994 | Jun 14 | Sep 12 | Apr 29 | Sep 21 |
| 1993 | Jun 17 | Aug 26 | May 3 | Sep 13 |
| 1992 | May 25 | Aug 22 | May 16 | Aug 22 |
| 1991 | no data | Sep 4 | no data | Sep 22 |
| 1990 | Jun 21 | Sep 14 | May 20 | Oct 6 |
| 1989 | May 31 | Sep 9 | May 30 | Sep 11 |
| 1988 | May 21 | Sep 11 | Apr 26 | Oct 18 |
| 1987 | May 24 | Sep 17 | May 22 | Oct 9 |
| 1986 | May 24 | Sep 4 | May 16 | Oct 2 |
| 1985 | Jun 26 | Sep 4 | May 12 | Sep 7 |
| 1984 | Jun 2 | Sep 13 | May 1 | Sep 23 |
| 1983 | May 31 | Sep 12 | May 19 | Sep 19 |
| 1982 | Jun 8 | Sep 14 | Jun 8 | Sep 15 |
| 1981 | no data | Sep 24 | no data | Sep 24 |
"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.