Last Frost Day

Frost history / Thiokol Propulsion F S, UT

Thiokol Propulsion F S, UT: frost dates by year

Last spring and first fall frost at NOAA station USC00428668, 1962 to 2009, measured from daily minimum temperatures.

Elevation 4,600 ft, 41.720, -112.426. Download the data (JSON), NOAA daily records

Summary at 32°F

Last spring frostFirst fall frost
MedianMay 20Sep 20
EarliestMay 1 (1998)Aug 26 (1992)
LatestJun 30 (1970)Oct 19 (1994)
Trend1.3 days earlier per decade1.9 days later per decade
Years with data4342

At 28°F (hard freeze) the median last spring date is May 8 and the median first fall date is Oct 1.

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 1419701980199020001963: May 131964: May 41965: May 271966: Jun 51967: May 151968: Jun 301969: May 161970: Jun 301971: May 191972: May 121973: Jun 191974: May 221975: Jun 41976: May 21977: May 171978: Jun 11979: Jun 81980: Jun 281981: May 131982: May 281983: May 141984: May 81985: May 141986: May 231987: May 31988: May 211989: Jun 211990: May 251991: May 201992: May 101993: Jun 131994: May 141995: Jun 71996: May 21997: Jun 211998: May 11999: May 172000: Jun 12001: Jun 132003: May 202004: May 292005: May 112006: May 10

First fall frost (32°F)

Aug 13Aug 28Sep 12Sep 27Oct 12Oct 2719701980199020001962: Sep 81963: Oct 141964: Aug 291965: Sep 171966: Oct 11967: Sep 131968: Sep 171969: Sep 231970: Sep 101971: Sep 181972: Sep 201974: Sep 121975: Sep 191976: Oct 51977: Sep 181978: Sep 191979: Oct 51980: Sep 221981: Sep 261982: Oct 21983: Sep 201984: Sep 221985: Sep 201986: Sep 271987: Sep 171988: Sep 181989: Sep 111990: Oct 81991: Sep 231992: Aug 261993: Sep 301994: Oct 191995: Sep 211996: Sep 181997: Oct 51998: Oct 41999: Sep 272001: Sep 72003: Sep 132004: Sep 142006: Oct 122009: Oct 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
2009no dataOct 3no dataOct 3
2006May 10Oct 12May 10Oct 22
2005May 11no dataApr 15no data
2004May 29Sep 14Apr 10Sep 21
2003May 20Sep 13May 20Sep 17
2001Jun 13Sep 7May 2Oct 10
2000Jun 1no dataMay 13no data
1999May 17Sep 27May 17Sep 27
1998May 1Oct 4Apr 18Oct 11
1997Jun 21Oct 5May 3Oct 8
1996May 2Sep 18Apr 29Oct 15
1995Jun 7Sep 21Apr 26Sep 22
1994May 14Oct 19Apr 30Oct 21
1993Jun 13Sep 30May 1Oct 19
1992May 10Aug 26Apr 24Sep 26
1991May 20Sep 23May 5Oct 4
1990May 25Oct 8May 16Oct 8
1989Jun 21Sep 11May 25Oct 4
1988May 21Sep 18May 4Sep 19
1987May 3Sep 17May 3Sep 18
1986May 23Sep 27May 23Sep 28
1985May 14Sep 20May 14Sep 23
1984May 8Sep 22May 8Sep 22
1983May 14Sep 20May 13Sep 20
1982May 28Oct 2May 7Oct 6
1981May 13Sep 26May 13Sep 26
1980Jun 28Sep 22Apr 17Oct 23
1979Jun 8Oct 5May 30Oct 21
1978Jun 1Sep 19May 31Sep 20
1977May 17Sep 18May 5Oct 11
1976May 2Oct 5Apr 19Oct 18
1975Jun 4Sep 19May 26Oct 9
1974May 22Sep 12Apr 29Sep 28
1973Jun 19no dataMay 8no data
1972May 12Sep 20May 10Sep 25
1971May 19Sep 18May 19Sep 19
1970Jun 30Sep 10May 15Sep 25
1969May 16Sep 23Apr 30Oct 3
1968Jun 30Sep 17May 16Sep 17
1967May 15Sep 13May 15Oct 8
1966Jun 5Oct 1May 23Oct 4
1965May 27Sep 17May 11Sep 17
1964May 4Aug 29May 4Sep 20
1963May 13Oct 14Apr 25Oct 24
1962no dataSep 8no dataSep 9

"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.