Last Frost Day

Frost history / Green Mt Dam, CO

Green Mt Dam, CO: frost dates by year

Last spring and first fall frost at NOAA station USC00053592, 1951 to 2008, measured from daily minimum temperatures.

Elevation 7,740 ft, 39.879, -106.333. Download the data (JSON) · NOAA daily records

Summary at 32°F

Last spring frostFirst fall frost
MedianJun 11Sep 5
EarliestMay 12 (1991)Aug 1 (1980)
LatestJul 31 (1980)Sep 27 (1981)
Trend0.5 days earlier per decadelittle change (less than half a day per decade)
Years with data4642

At 28°F (hard freeze) the median last spring date is May 23 and the median first fall date is Sep 21.

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 13196019701980199020001951: Jun 241952: Jun 171953: Jun 251954: Jun 121955: Jun 111956: May 171957: Jun 221958: May 151959: Jul 171960: Jun 131961: Jun 41962: Jun 181963: Jun 101964: Jun 231965: Jun 21966: Jun 131967: Jun 11968: Jul 11969: Jun 21970: Jun 21971: Jun 51972: May 291973: Jun 191974: Jun 111975: Jun 261976: Jun 251977: Jun 61978: Jun 21979: Jun 101980: Jul 311981: Jun 161982: Jun 121983: May 221984: Jun 101985: Jun 271987: May 291988: Jun 11989: Jun 221990: Jun 161991: May 121992: Jun 81996: Jun 21997: Jul 32004: Jun 222006: Jun 22008: Jun 12

First fall frost (32°F)

Jul 14Jul 29Aug 13Aug 28Sep 12Sep 27Oct 12196019701980199020001951: Aug 231952: Sep 21953: Sep 41954: Sep 211955: Sep 111956: Sep 11957: Sep 111958: Aug 241959: Sep 21960: Sep 101961: Sep 21962: Aug 311963: Sep 251964: Aug 281965: Sep 11966: Aug 221967: Sep 131968: Aug 241969: Sep 231970: Sep 101971: Sep 151972: Sep 211973: Sep 31974: Sep 31975: Sep 191976: Aug 281977: Sep 181978: Aug 151979: Sep 131980: Aug 11981: Sep 271982: Sep 61983: Sep 161984: Sep 241988: Sep 151989: Sep 111990: Aug 221991: Sep 141994: Sep 162004: Aug 282005: Aug 312006: Aug 29

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
2008Jun 12no dataMay 11no data
2006Jun 2Aug 29May 31Sep 2
2005no dataAug 31no dataSep 15
2004Jun 22Aug 28May 31Sep 15
1997Jul 3no dataMay 9no data
1996Jun 2no dataMay 9no data
1994no dataSep 16no dataSep 22
1992Jun 8no dataApr 19no data
1991May 12Sep 14May 5Sep 15
1990Jun 16Aug 22May 26Sep 22
1989Jun 22Sep 11Jun 22Sep 11
1988Jun 1Sep 15May 22Sep 19
1987May 29no dataApr 23no data
1985Jun 27no dataMay 14no data
1984Jun 10Sep 24May 9Sep 25
1983May 22Sep 16May 18Sep 20
1982Jun 12Sep 6May 7Oct 3
1981Jun 16Sep 27Apr 10Oct 19
1980Jul 31Aug 1Jul 29Aug 13
1979Jun 10Sep 13Jun 1Sep 15
1978Jun 2Aug 15May 19Aug 19
1977Jun 6Sep 18May 28Sep 24
1976Jun 25Aug 28Jun 14Sep 9
1975Jun 26Sep 19May 30Sep 20
1974Jun 11Sep 3May 23Sep 3
1973Jun 19Sep 3Jun 5Sep 17
1972May 29Sep 21May 23Sep 21
1971Jun 5Sep 15May 24Sep 17
1970Jun 2Sep 10Jun 1Sep 23
1969Jun 2Sep 23May 6Oct 4
1968Jul 1Aug 24May 24Sep 23
1967Jun 1Sep 13May 30Oct 7
1966Jun 13Aug 22Jun 2Oct 1
1965Jun 2Sep 1May 16Sep 1
1964Jun 23Aug 28May 31Aug 28
1963Jun 10Sep 25May 13Oct 17
1962Jun 18Aug 31Jun 9Sep 9
1961Jun 4Sep 2May 17Sep 13
1960Jun 13Sep 10May 20Oct 6
1959Jul 17Sep 2May 24Sep 28
1958May 15Aug 24May 3Aug 25
1957Jun 22Sep 11May 23Sep 22
1956May 17Sep 1May 15Sep 23
1955Jun 11Sep 11May 29Sep 27
1954Jun 12Sep 21Jun 3Oct 14
1953Jun 25Sep 4May 22Sep 24
1952Jun 17Sep 2May 17Sep 22
1951Jun 24Aug 23Jun 5Aug 23

"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.