Last Frost Day

Frost history / Divide, MT

Divide, MT: frost dates by year

Last spring and first fall frost at NOAA station USC00242421, 1951 to 2023, measured from daily minimum temperatures.

Elevation 5,350 ft, 45.751, -112.755. Download the data (JSON), NOAA daily records

Summary at 32°F

Last spring frostFirst fall frost
MedianJun 13Sep 9
EarliestApr 27 (1957)Aug 14 (2005)
LatestJul 8 (2004)Oct 18 (1963)
Trend2.0 days later per decade1.0 days earlier per decade
Years with data5357

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

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 1419601970198019902000201020201951: Jun 71952: Jun 231953: Jun 251954: Jun 181955: Jun 301956: May 131957: Apr 271958: May 141959: May 301960: Jun 211961: May 111962: Jun 71963: Jun 301964: May 261965: Jun 131966: Jun 51967: May 261968: Jun 141969: Jun 291970: Jun 111971: Jul 71972: May 261974: Jun 81975: Jun 281976: Jun 271977: May 301978: Jun 161979: Jun 81980: May 241981: Jul 81982: Jun 51983: Jun 191984: Jun 91985: May 311986: May 231987: Jun 31988: May 201989: May 311990: Jun 11991: Jun 181992: May 161993: Jun 131994: Jun 152004: Jul 82005: Jun 132007: May 302008: Jun 142009: Jun 232010: Jul 72011: Jun 272012: Jun 272013: Jun 152014: Jun 15

First fall frost (32°F)

Jul 29Aug 13Aug 28Sep 12Sep 27Oct 12Oct 2719601970198019902000201020201951: Sep 41952: Sep 11953: Sep 201954: Sep 191955: Sep 191956: Sep 31957: Sep 101958: Sep 31959: Sep 11960: Aug 261961: Sep 121962: Sep 31963: Oct 181964: Sep 101965: Aug 301966: Aug 211967: Oct 11968: Sep 201969: Sep 41970: Sep 111971: Sep 151972: Sep 71973: Sep 141974: Sep 21975: Sep 181976: Aug 271977: Aug 311978: Aug 171979: Sep 121980: Aug 291981: Sep 201982: Sep 111983: Sep 101984: Sep 101985: Sep 131986: Sep 121987: Sep 171988: Sep 111989: Sep 101990: Oct 31991: Sep 181992: Aug 231993: Aug 301994: Oct 22003: Sep 92004: Sep 32005: Aug 142006: Aug 312007: Sep 102008: Sep 22009: Sep 72010: Sep 22011: Sep 32012: Sep 22013: Aug 242014: Sep 42023: Sep 15

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
2023no dataSep 15no dataSep 28
2014Jun 15Sep 4May 12Sep 6
2013Jun 15Aug 24May 2Sep 27
2012Jun 27Sep 2May 28Sep 12
2011Jun 27Sep 3Jun 4Sep 4
2010Jul 7Sep 2May 26Sep 7
2009Jun 23Sep 7May 21Sep 7
2008Jun 14Sep 2May 13Sep 8
2007May 30Sep 10May 15Sep 14
2006no dataAug 31no dataAug 31
2005Jun 13Aug 14May 26Sep 14
2004Jul 8Sep 3May 25Sep 21
2003no dataSep 9no dataSep 17
1994Jun 15Oct 2Apr 30Oct 3
1993Jun 13Aug 30May 9Sep 17
1992May 16Aug 23May 12Aug 25
1991Jun 18Sep 18May 5Sep 18
1990Jun 1Oct 3Jun 1Oct 6
1989May 31Sep 10May 24Sep 11
1988May 20Sep 11May 3Oct 18
1987Jun 3Sep 17May 3Sep 17
1986May 23Sep 12May 23Sep 27
1985May 31Sep 13May 14Sep 23
1984Jun 9Sep 10Jun 9Sep 14
1983Jun 19Sep 10May 14Sep 10
1982Jun 5Sep 11May 31Sep 11
1981Jul 8Sep 20May 8Sep 22
1980May 24Aug 29May 12Sep 22
1979Jun 8Sep 12May 30Oct 18
1978Jun 16Aug 17May 26Sep 17
1977May 30Aug 31May 30Sep 23
1976Jun 27Aug 27May 16Sep 8
1975Jun 28Sep 18May 26Sep 19
1974Jun 8Sep 2May 17Sep 13
1973no dataSep 14no dataOct 3
1972May 26Sep 7May 2Sep 21
1971Jul 7Sep 15May 19Sep 15
1970Jun 11Sep 11May 14Sep 12
1969Jun 29Sep 4Jun 14Oct 5
1968Jun 14Sep 20May 11Sep 21
1967May 26Oct 1May 26Oct 4
1966Jun 5Aug 21May 23Sep 30
1965Jun 13Aug 30May 18Aug 30
1964May 26Sep 10May 5Sep 19
1963Jun 30Oct 18May 19Oct 24
1962Jun 7Sep 3May 12Sep 9
1961May 11Sep 12May 8Sep 13
1960Jun 21Aug 26May 24Sep 22
1959May 30Sep 1May 23Sep 29
1958May 14Sep 3May 1Sep 24
1957Apr 27Sep 10Apr 27Sep 18
1956May 13Sep 3May 12Sep 3
1955Jun 30Sep 19Jun 1Sep 22
1954Jun 18Sep 19Jun 18Sep 30
1953Jun 25Sep 20May 23Oct 3
1952Jun 23Sep 1May 5Oct 5
1951Jun 7Sep 4Jun 3Sep 27

"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.