Frost history / Thermopolis 21WNW, WY
Thermopolis 21WNW, WY: frost dates by year
Last spring and first fall frost at NOAA station USC00488888, 1957 to 2011, measured from daily minimum temperatures.
Elevation 5,510 ft, 43.723, -108.696. Download the data (JSON), NOAA daily records
Summary at 32°F
| Last spring frost | First fall frost | |
|---|---|---|
| Median | Jun 7 | Sep 5 |
| Earliest | May 1 (1958) | Aug 18 (1992) |
| Latest | Jul 1 (1968) | Oct 10 (1963) |
| Trend | 1.0 days earlier per decade | 1.6 days later per decade |
| Years with data | 36 | 29 |
At 28°F (hard freeze) the median last spring date is May 13 and the median first fall date is Sep 20.
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 |
|---|---|---|---|---|
| 2011 | Jun 10 | Sep 15 | May 28 | Sep 21 |
| 2010 | Jun 18 | Sep 3 | May 23 | Sep 7 |
| 2009 | May 16 | no data | May 16 | no data |
| 2008 | Jun 13 | Sep 2 | May 3 | Oct 8 |
| 2007 | Jun 8 | no data | Apr 23 | no data |
| 2005 | Jun 8 | no data | May 13 | no data |
| 2004 | May 31 | no data | May 30 | no data |
| 2003 | May 20 | Sep 9 | May 20 | Sep 18 |
| 2002 | Jun 19 | Sep 22 | Jun 11 | Sep 22 |
| 2001 | Jun 13 | Sep 8 | May 22 | Oct 4 |
| 2000 | no data | Sep 20 | no data | Sep 20 |
| 1999 | May 17 | no data | May 11 | no data |
| 1998 | Jun 6 | Sep 27 | May 9 | Oct 6 |
| 1996 | May 24 | no data | May 19 | no data |
| 1995 | May 24 | Sep 20 | May 14 | Sep 21 |
| 1994 | May 21 | no data | Apr 30 | no data |
| 1993 | no data | Aug 27 | no data | Sep 13 |
| 1992 | May 17 | Aug 18 | May 13 | Aug 24 |
| 1991 | May 28 | Sep 18 | May 5 | Sep 18 |
| 1990 | no data | Sep 29 | no data | Oct 2 |
| 1989 | no data | Aug 26 | no data | Sep 10 |
| 1988 | Jun 1 | Sep 11 | May 4 | Oct 18 |
| 1987 | Jun 23 | Sep 17 | Apr 21 | Sep 17 |
| 1986 | May 24 | no data | May 23 | no data |
| 1982 | Jun 9 | no data | May 31 | no data |
| 1977 | no data | Aug 31 | no data | Sep 9 |
| 1975 | no data | Aug 26 | no data | Sep 20 |
| 1974 | Jun 9 | no data | May 22 | no data |
| 1973 | Jun 18 | no data | May 13 | no data |
| 1970 | Jun 13 | no data | May 13 | no data |
| 1969 | Jun 29 | Sep 15 | May 8 | Oct 5 |
| 1968 | Jul 1 | Sep 5 | May 20 | Sep 22 |
| 1967 | Jun 24 | no data | May 12 | no data |
| 1966 | Jun 13 | no data | May 23 | no data |
| 1965 | May 27 | Aug 30 | May 18 | Sep 4 |
| 1964 | May 24 | Aug 20 | May 12 | Sep 11 |
| 1963 | Jun 30 | Oct 10 | May 2 | Oct 24 |
| 1962 | Jun 6 | Sep 5 | May 1 | Sep 8 |
| 1961 | May 17 | Sep 2 | May 8 | Sep 3 |
| 1960 | Jun 21 | Aug 24 | May 20 | Sep 23 |
| 1959 | May 29 | Sep 2 | May 21 | Sep 22 |
| 1958 | May 1 | Sep 3 | May 1 | Sep 20 |
| 1957 | no data | Sep 11 | no data | Sep 14 |
"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.