Last Frost Day

Frost history / Carter 14 W, MT

Carter 14 W, MT: frost dates by year

Last spring and first fall frost at NOAA station USC00241525, 1983 to 2024, measured from daily minimum temperatures.

Elevation 3,450 ft, 47.792, -111.220. Download the data (JSON), NOAA daily records

Summary at 32°F

Last spring frostFirst fall frost
MedianMay 23Sep 21
EarliestApr 27 (2023)Aug 22 (1992)
LatestJul 16 (1999)Oct 9 (2008)
Trend1.7 days earlier per decade2.1 days later per decade
Years with data3738

At 28°F (hard freeze) the median last spring date is May 4 and the median first fall date is Oct 5.

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)

Apr 15Apr 30May 15May 30Jun 14Jun 29Jul 14Jul 2919902000201020201983: May 311984: May 231985: Jun 11986: May 151987: May 221988: May 31989: May 291990: May 201991: May 51992: May 251993: Jun 31994: Jun 151995: May 261996: May 121997: May 191998: May 191999: Jul 162000: Jun 22001: Jun 42002: May 232003: May 192004: Jun 182005: May 312006: May 142007: May 242008: Jun 112009: Jun 82010: May 212012: May 272013: May 152016: May 152019: May 192020: May 122021: May 232022: May 222023: Apr 272024: May 21

First fall frost (32°F)

Aug 13Aug 28Sep 12Sep 27Oct 12Oct 2719902000201020201983: Sep 181984: Sep 131985: Sep 181986: Sep 71987: Oct 71988: Sep 111989: Sep 101990: Oct 61991: Sep 181992: Aug 221993: Sep 171994: Oct 21995: Sep 201996: Sep 241997: Sep 191998: Oct 41999: Sep 272000: Sep 202001: Oct 22002: Sep 252003: Sep 172004: Oct 12005: Sep 272006: Sep 162007: Sep 132008: Oct 92009: Sep 282010: Sep 172011: Sep 292012: Sep 122015: Sep 282016: Sep 132019: Sep 282020: Sep 72021: Oct 22022: Sep 212023: Oct 62024: Sep 30

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
2024May 21Sep 30May 4Oct 13
2023Apr 27Oct 6Apr 23Oct 20
2022May 22Sep 21May 22Oct 23
2021May 23Oct 2May 22Oct 8
2020May 12Sep 7Apr 19Oct 14
2019May 19Sep 28May 7Sep 28
2016May 15Sep 13May 15Sep 13
2015no dataSep 28no dataOct 5
2013May 15no dataMay 2no data
2012May 27Sep 12May 25Oct 4
2011no dataSep 29no dataOct 14
2010May 21Sep 17May 10Oct 16
2009Jun 8Sep 28May 3Sep 28
2008Jun 11Oct 9May 1Oct 9
2007May 24Sep 13Apr 22Oct 26
2006May 14Sep 16May 4Oct 9
2005May 31Sep 27May 30Oct 6
2004Jun 18Oct 1May 17Oct 1
2003May 19Sep 17May 8Sep 18
2002May 23Sep 25May 23Sep 25
2001Jun 4Oct 2Apr 22Oct 4
2000Jun 2Sep 20May 8Sep 22
1999Jul 16Sep 27May 8Oct 1
1998May 19Oct 4May 8Oct 20
1997May 19Sep 19Apr 23Oct 9
1996May 12Sep 24May 9Sep 24
1995May 26Sep 20May 1Sep 21
1994Jun 15Oct 2Apr 29Oct 24
1993Jun 3Sep 17Apr 1Sep 22
1992May 25Aug 22May 22Oct 14
1991May 5Sep 18May 2Sep 18
1990May 20Oct 6May 9Oct 6
1989May 29Sep 10Apr 30Sep 11
1988May 3Sep 11May 3Oct 18
1987May 22Oct 7May 20Oct 9
1986May 15Sep 7Apr 29Oct 11
1985Jun 1Sep 18Apr 25Sep 27
1984May 23Sep 13May 1Sep 23
1983May 31Sep 18May 12Sep 19

"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.