Frost history / Blackleaf, MT
Blackleaf, MT: frost dates by year
Last spring and first fall frost at NOAA station USC00240877, 1954 to 2003, measured from daily minimum temperatures.
Elevation 4,235 ft, 48.013, -112.437. Download the data (JSON), NOAA daily records
Summary at 32°F
| Last spring frost | First fall frost | |
|---|---|---|
| Median | Jun 7 | Sep 3 |
| Earliest | May 13 (1981) | Aug 5 (1959) |
| Latest | Jul 31 (1968) | Sep 21 (1998) |
| Trend | 0.5 days later per decade | 1.2 days later per decade |
| Years with data | 36 | 34 |
At 28°F (hard freeze) the median last spring date is May 20 and the median first fall date is Sep 17.
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 |
|---|---|---|---|---|
| 2003 | Jun 7 | no data | May 21 | no data |
| 2002 | no data | Aug 17 | no data | Sep 25 |
| 2000 | no data | Sep 11 | no data | Sep 11 |
| 1999 | no data | Sep 3 | no data | Sep 19 |
| 1998 | Jun 9 | Sep 21 | May 19 | Sep 21 |
| 1997 | Jun 24 | no data | May 19 | no data |
| 1995 | Jun 7 | Sep 19 | May 27 | Sep 20 |
| 1994 | Jun 17 | no data | Jun 17 | no data |
| 1993 | Jun 3 | Aug 25 | May 4 | Sep 13 |
| 1992 | Jul 2 | Aug 22 | May 24 | Aug 24 |
| 1991 | Jun 18 | no data | May 26 | no data |
| 1990 | no data | Sep 2 | no data | Sep 29 |
| 1988 | May 25 | Sep 11 | May 3 | Sep 12 |
| 1987 | Jun 3 | Aug 26 | Apr 20 | Sep 17 |
| 1986 | no data | Sep 6 | no data | Sep 6 |
| 1985 | Jun 26 | no data | May 16 | no data |
| 1983 | Jun 3 | Sep 14 | Jun 1 | Sep 19 |
| 1982 | Jun 8 | Sep 12 | Jun 8 | Sep 15 |
| 1981 | May 13 | no data | May 5 | no data |
| 1979 | no data | Sep 14 | no data | Oct 3 |
| 1977 | May 29 | no data | May 27 | no data |
| 1976 | Jun 18 | Sep 8 | Jun 18 | Sep 8 |
| 1975 | May 26 | Sep 4 | May 2 | Sep 12 |
| 1974 | May 23 | Sep 2 | May 15 | Sep 2 |
| 1973 | Jun 11 | no data | Jun 11 | no data |
| 1972 | Jun 19 | Sep 1 | May 10 | Sep 21 |
| 1971 | Jul 4 | no data | May 15 | no data |
| 1970 | May 31 | Sep 9 | May 13 | Sep 9 |
| 1969 | Jun 14 | Aug 17 | Jun 14 | Sep 1 |
| 1968 | Jul 31 | Sep 20 | May 20 | Sep 21 |
| 1967 | May 26 | Sep 14 | May 26 | Sep 23 |
| 1966 | no data | Aug 12 | no data | Sep 30 |
| 1965 | Jun 8 | no data | May 18 | no data |
| 1964 | May 26 | Aug 31 | May 26 | Sep 21 |
| 1963 | Jun 26 | Sep 16 | May 23 | Sep 19 |
| 1962 | Jun 2 | Aug 30 | May 5 | Sep 3 |
| 1961 | May 17 | Sep 2 | May 12 | Sep 8 |
| 1960 | Jun 18 | Sep 7 | May 24 | Sep 7 |
| 1959 | May 27 | Aug 5 | May 27 | Sep 9 |
| 1958 | Jun 25 | Sep 3 | Apr 29 | Sep 29 |
| 1957 | May 24 | Sep 18 | May 22 | Sep 18 |
| 1956 | May 29 | Aug 19 | May 13 | Sep 2 |
| 1955 | Jul 3 | Aug 28 | May 25 | Sep 25 |
| 1954 | no data | Sep 4 | no data | Sep 29 |
"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.