Last Frost Day

Frost history / Weston 1 E, WY

Weston 1 E, WY: frost dates by year

Last spring and first fall frost at NOAA station USC00489580, 1961 to 2025, measured from daily minimum temperatures.

Elevation 3,738 ft, 44.640, -105.301. Download the data (JSON), NOAA daily records

Summary at 32°F

Last spring frostFirst fall frost
MedianMay 23Sep 17
EarliestApr 14 (1981)Aug 17 (2002)
LatestJun 30 (1995)Oct 10 (1963)
Trend1.0 days later per decade0.9 days later per decade
Years with data5556

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)

Mar 31Apr 15Apr 30May 15May 30Jun 14Jun 29Jul 141970198019902000201020201961: May 81962: Jun 51963: May 221964: Jun 21965: May 271966: May 241967: May 121968: May 231969: Jun 141970: May 21971: May 201972: May 21973: May 221974: Jun 11975: May 261976: May 161977: May 211978: May 91979: Jun 81980: May 141981: Apr 141982: May 311983: Jun 61984: Jun 21985: May 151986: May 251987: May 41988: May 221989: May 261990: May 171991: May 61992: May 171993: May 241994: May 41995: Jun 301996: May 211997: May 281998: Jun 61999: Jun 172000: Jun 22002: May 242003: May 202013: May 112014: May 152015: May 212016: Jun 12017: May 292018: May 22019: Jun 92020: May 252021: May 302022: May 232023: May 192024: Jun 202025: May 22

First fall frost (32°F)

Jul 29Aug 13Aug 28Sep 12Sep 27Oct 12Oct 271970198019902000201020201961: Sep 31963: Oct 101964: Sep 121965: Sep 51966: Aug 221967: Sep 271968: Sep 51969: Sep 271970: Sep 121971: Sep 151972: Sep 211973: Sep 151974: Sep 131975: Sep 121976: Sep 91977: Sep 91979: Sep 111980: Sep 91981: Oct 11982: Sep 201983: Sep 191984: Sep 131985: Sep 231986: Sep 291987: Sep 181988: Aug 281989: Sep 111990: Sep 141991: Sep 181992: Aug 301994: Sep 221995: Sep 211997: Sep 201998: Oct 61999: Sep 132000: Sep 222001: Sep 232002: Aug 172003: Sep 182005: Sep 292009: Sep 232010: Sep 32012: Sep 122013: Sep 202014: Sep 112015: Aug 232016: Oct 42017: Sep 42018: Sep 252019: Oct 12020: Sep 82021: Sep 212022: Oct 62023: Oct 62024: Sep 222025: Sep 5

Dots are single years. The gray line is the median, the green line the fitted trend.

Year by year

YearLast spring 32°FFirst fall 32°FLast spring 28°FFirst fall 28°F
2025May 22Sep 5Apr 22Oct 13
2024Jun 20Sep 22May 4Oct 6
2023May 19Oct 6May 8Oct 6
2022May 23Oct 6May 22Oct 8
2021May 30Sep 21May 10Oct 14
2020May 25Sep 8May 10Sep 9
2019Jun 9Oct 1May 12Oct 3
2018May 2Sep 25Apr 24Oct 3
2017May 29Sep 4Apr 29Sep 4
2016Jun 1Oct 4May 15Oct 5
2015May 21Aug 23May 11Oct 15
2014May 15Sep 11May 15Sep 13
2013May 11Sep 20May 5Oct 5
2012no dataSep 12no dataOct 4
2010no dataSep 3no dataOct 13
2009no dataSep 23no dataSep 28
2005no dataSep 29no dataOct 5
2003May 20Sep 18May 20Sep 18
2002May 24Aug 17May 24Sep 26
2001no dataSep 23no dataOct 5
2000Jun 2Sep 22May 13Sep 23
1999Jun 17Sep 13May 7Sep 13
1998Jun 6Oct 6May 8Oct 20
1997May 28Sep 20May 19Oct 6
1996May 21no dataMay 11no data
1995Jun 30Sep 21Apr 27Sep 21
1994May 4Sep 22Apr 29Sep 22
1993May 24no dataMay 1no data
1992May 17Aug 30May 2Sep 10
1991May 6Sep 18May 5Sep 18
1990May 17Sep 14May 10Oct 3
1989May 26Sep 11May 1Sep 11
1988May 22Aug 28May 21Oct 8
1987May 4Sep 18Apr 22Oct 5
1986May 25Sep 29May 24Sep 30
1985May 15Sep 23May 14Sep 23
1984Jun 2Sep 13May 1Sep 24
1983Jun 6Sep 19May 17Sep 20
1982May 31Sep 20May 6Oct 11
1981Apr 14Oct 1Apr 14Oct 6
1980May 14Sep 9May 13Oct 10
1979Jun 8Sep 11May 11Sep 14
1978May 9no dataApr 24no data
1977May 21Sep 9Apr 25Sep 24
1976May 16Sep 9May 7Sep 27
1975May 26Sep 12Apr 21Sep 20
1974Jun 1Sep 13May 22Sep 13
1973May 22Sep 15May 13Oct 4
1972May 2Sep 21Apr 28Sep 21
1971May 20Sep 15May 11Sep 16
1970May 2Sep 12Apr 26Sep 15
1969Jun 14Sep 27Jun 14Oct 5
1968May 23Sep 5May 20Sep 23
1967May 12Sep 27May 11Oct 15
1966May 24Aug 22May 19Oct 10
1965May 27Sep 5May 27Sep 16
1964Jun 2Sep 12Apr 21Sep 12
1963May 22Oct 10May 22Oct 11
1962Jun 5no dataApr 30no data
1961May 8Sep 3May 8Sep 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.