Last Frost Day

Frost history / Denton, MT

Denton, MT: frost dates by year

Last spring and first fall frost at NOAA station USC00242347, 1963 to 2014, measured from daily minimum temperatures.

Elevation 3,610 ft, 47.318, -109.937. Download the data (JSON), NOAA daily records

Summary at 32°F

Last spring frostFirst fall frost
MedianJun 8Sep 5
EarliestMay 14 (2006)Aug 3 (1978)
LatestJul 29 (1971)Sep 27 (2013)
Trend3.5 days earlier per decade0.7 days later per decade
Years with data4442

At 28°F (hard freeze) the median last spring date is May 19 and the median first fall date is Sep 18.

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 30May 15May 30Jun 14Jun 29Jul 14Jul 29Aug 13197019801990200020101963: Jun 231964: May 301965: Jun 81968: May 251969: Jun 161970: May 251971: Jul 291972: Jul 41973: Jul 21974: Jun 71975: May 291976: Jun 271977: May 281978: Jun 201979: Jun 81980: May 271981: Jul 91985: Jun 271988: Jun 11989: Jun 261990: Jun 131991: Jun 181992: Jun 71993: Jun 171994: Jun 171995: May 271997: May 191998: Jun 91999: Jul 172000: Jun 302001: May 302002: May 232003: May 202004: May 232005: May 312006: May 142007: May 142008: Jun 102009: Jun 102010: Jun 122011: May 182012: May 282013: Jun 52014: Jun 12

First fall frost (32°F)

Jul 29Aug 13Aug 28Sep 12Sep 27Oct 12197019801990200020101964: Sep 31965: Sep 71967: Sep 231968: Sep 81969: Aug 301970: Sep 101972: Sep 71974: Sep 21975: Sep 121976: Sep 91977: Aug 111978: Aug 31979: Sep 51980: Aug 281981: Aug 311982: Sep 111983: Sep 61984: Sep 131985: Aug 171986: Sep 71987: Aug 121988: Aug 221990: Sep 141991: Sep 31992: Aug 231993: Aug 301995: Aug 141996: Aug 191997: Sep 91998: Sep 211999: Sep 82000: Sep 202001: Sep 202002: Aug 172003: Sep 142004: Sep 22006: Sep 152008: Sep 12010: Sep 62011: Sep 22012: Aug 242013: Sep 27

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
2014Jun 12no dataMay 12no data
2013Jun 5Sep 27May 15Sep 27
2012May 28Aug 24May 28Sep 12
2011May 18Sep 2May 18Sep 20
2010Jun 12Sep 6May 19Oct 12
2009Jun 10no dataJun 7no data
2008Jun 10Sep 1May 2Sep 7
2007May 14no dataMay 14no data
2006May 14Sep 15May 5Oct 9
2005May 31no dataMay 30no data
2004May 23Sep 2May 23Sep 3
2003May 20Sep 14May 17Sep 18
2002May 23Aug 17May 23Sep 22
2001May 30Sep 20May 30Oct 5
2000Jun 30Sep 20May 24Sep 22
1999Jul 17Sep 8Jul 17Sep 8
1998Jun 9Sep 21Jun 4Sep 21
1997May 19Sep 9May 19Sep 19
1996no dataAug 19no dataSep 24
1995May 27Aug 14May 23Sep 21
1994Jun 17no dataMay 4no data
1993Jun 17Aug 30May 10Sep 14
1992Jun 7Aug 23Jun 6Aug 25
1991Jun 18Sep 3Jun 15Sep 18
1990Jun 13Sep 14May 9Sep 22
1989Jun 26no dataMay 21no data
1988Jun 1Aug 22May 3Sep 19
1987no dataAug 12no dataAug 12
1986no dataSep 7no dataSep 27
1985Jun 27Aug 17May 16Sep 20
1984no dataSep 13no dataSep 13
1983no dataSep 6no dataSep 19
1982no dataSep 11no dataSep 15
1981Jul 9Aug 31May 3Sep 23
1980May 27Aug 28May 15Aug 30
1979Jun 8Sep 5Jun 8Sep 29
1978Jun 20Aug 3May 4Sep 17
1977May 28Aug 11May 28Aug 11
1976Jun 27Sep 9May 21Sep 9
1975May 29Sep 12May 26Sep 12
1974Jun 7Sep 2May 17Sep 2
1973Jul 2no dataMay 12no data
1972Jul 4Sep 7May 2Sep 7
1971Jul 29no dataMay 10no data
1970May 25Sep 10Apr 29Sep 10
1969Jun 16Aug 30Jun 14Aug 30
1968May 25Sep 8May 19Oct 3
1967no dataSep 23no dataOct 13
1965Jun 8Sep 7May 22Sep 13
1964May 30Sep 3May 26Sep 11
1963Jun 23no dataMay 21no data

"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.