Last Frost Day

Frost history / Content 4 Nne, MT

Content 4 Nne, MT: frost dates by year

Last spring and first fall frost at NOAA station USC00241984, 1966 to 2025, measured from daily minimum temperatures.

Elevation 2,325 ft, 48.080, -107.525. Download the data (JSON) · NOAA daily records

Summary at 32°F

Last spring frostFirst fall frost
MedianMay 18Sep 14
EarliestApr 20 (1987)Aug 13 (2005)
LatestJun 26 (1989)Oct 6 (2023)
Trendlittle change (less than half a day per decade)0.7 days later per decade
Years with data5253

At 28°F (hard freeze) the median last spring date is May 9 and the median first fall date is Sep 28.

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 141970198019902000201020201967: May 161968: May 231969: Jun 11970: May 121971: May 181972: May 61973: May 131975: May 291976: May 211977: May 301980: May 141981: May 241982: Jun 71983: May 141985: May 141986: May 161987: Apr 201988: May 31989: Jun 261990: May 141991: May 51992: May 251993: Jun 31994: May 41996: May 111997: May 151998: Jun 31999: May 172000: May 232001: May 212002: May 232003: May 202004: Jun 182005: May 312006: May 142007: May 242008: May 102009: Jun 102010: May 132012: May 292014: May 142015: May 192016: May 142017: May 292018: May 12019: May 192020: May 132021: May 212022: Jun 12023: Apr 232024: May 312025: May 14

First fall frost (32°F)

Jul 29Aug 13Aug 28Sep 12Sep 27Oct 121970198019902000201020201966: Sep 141967: Sep 271968: Sep 41970: Sep 121971: Sep 151972: Sep 11973: Sep 141974: Sep 11975: Sep 121976: Sep 91977: Sep 261979: Sep 131980: Sep 161981: Sep 271982: Sep 131983: Sep 121984: Sep 231985: Sep 201986: Sep 61987: Oct 51988: Sep 121989: Sep 111990: Sep 211991: Sep 61992: Aug 301993: Sep 141995: Sep 201997: Sep 191998: Oct 61999: Sep 92000: Sep 112001: Oct 32002: Sep 262004: Sep 212005: Aug 132006: Sep 282007: Sep 142008: Sep 242009: Sep 282011: Sep 212013: Oct 12014: Sep 122015: Aug 222016: Sep 122017: Sep 42018: Sep 272019: Sep 302020: Aug 302021: Sep 162022: Sep 92023: Oct 62024: Sep 292025: Sep 3

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 14Sep 3Apr 23Oct 5
2024May 31Sep 29Apr 22Oct 4
2023Apr 23Oct 6Apr 23Oct 24
2022Jun 1Sep 9May 20Sep 19
2021May 21Sep 16May 9Sep 29
2020May 13Aug 30May 10Sep 27
2019May 19Sep 30May 10Sep 30
2018May 1Sep 27Apr 25Sep 27
2017May 29Sep 4Apr 28Oct 3
2016May 14Sep 12May 13Sep 12
2015May 19Aug 22May 17Sep 27
2014May 14Sep 12May 12Oct 3
2013no dataOct 1no dataOct 1
2012May 29no dataMay 11no data
2011no dataSep 21no dataOct 14
2010May 13no dataMay 8no data
2009Jun 10Sep 28May 13Sep 28
2008May 10Sep 24May 10Oct 7
2007May 24Sep 14Apr 16Oct 4
2006May 14Sep 28May 5Oct 9
2005May 31Aug 13May 14Sep 28
2004Jun 18Sep 21May 13Oct 1
2003May 20no dataMay 20no data
2002May 23Sep 26May 11Oct 2
2001May 21Oct 3May 21Oct 3
2000May 23Sep 11Apr 27Sep 23
1999May 17Sep 9May 7Oct 2
1998Jun 3Oct 6May 7Oct 6
1997May 15Sep 19May 15Sep 19
1996May 11no dataMay 9no data
1995no dataSep 20no dataSep 20
1994May 4no dataApr 30no data
1993Jun 3Sep 14Apr 20Sep 14
1992May 25Aug 30Apr 25Sep 6
1991May 5Sep 6May 5Sep 18
1990May 14Sep 21May 11Sep 21
1989Jun 26Sep 11Jun 26Sep 11
1988May 3Sep 12Apr 27Oct 23
1987Apr 20Oct 5Apr 20Oct 6
1986May 16Sep 6Apr 16Oct 11
1985May 14Sep 20May 5Sep 23
1984no dataSep 23no dataSep 23
1983May 14Sep 12May 12Sep 12
1982Jun 7Sep 13May 5Sep 19
1981May 24Sep 27May 4Sep 27
1980May 14Sep 16May 11Sep 25
1979no dataSep 13no dataOct 9
1977May 30Sep 26May 6Oct 4
1976May 21Sep 9May 7Oct 5
1975May 29Sep 12Apr 22Sep 12
1974no dataSep 1no dataSep 2
1973May 13Sep 14May 12Sep 16
1972May 6Sep 1May 6Sep 21
1971May 18Sep 15May 10Sep 21
1970May 12Sep 12May 12Sep 12
1969Jun 1no dataMay 20no data
1968May 23Sep 4May 23Oct 3
1967May 16Sep 27May 12Oct 17
1966no dataSep 14no dataOct 10

"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 1991–2020 frost probabilities.