Last Frost Day

Frost history / Grand Portage, MN

Grand Portage, MN: frost dates by year

Last spring and first fall frost at NOAA station USC00213296, 1962 to 2025, measured from daily minimum temperatures.

Elevation 730 ft, 47.971, -89.691. Download the data (JSON), NOAA daily records

Summary at 32°F

Last spring frostFirst fall frost
MedianMay 22Sep 29
EarliestMay 9 (1962)Sep 2 (1976)
LatestJun 5 (1964)Oct 21 (2021)
Trendlittle change (less than half a day per decade)2.5 days later per decade
Years with data3738

At 28°F (hard freeze) the median last spring date is May 8 and the median first fall date is Oct 7.

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 141970198019902000201020201962: May 91963: May 241964: Jun 51965: May 291966: May 141967: May 221968: May 101969: May 261970: May 281971: Jun 11995: May 151997: May 231998: Jun 31999: May 92000: May 202001: May 132002: May 262003: May 222004: May 292005: May 172006: May 232007: May 212008: May 282010: May 162011: May 272012: May 172013: Jun 32014: May 172015: Jun 12017: May 202018: May 202019: May 212021: May 292022: May 242023: May 252024: May 102025: May 19

First fall frost (32°F)

Aug 28Sep 12Sep 27Oct 12Oct 271970198019902000201020201963: Sep 131964: Sep 151965: Sep 241966: Sep 261967: Sep 101968: Oct 51969: Sep 241970: Sep 281976: Sep 21994: Oct 31996: Sep 291997: Oct 11998: Oct 11999: Sep 212000: Sep 242001: Sep 252002: Sep 232003: Sep 292004: Sep 292005: Sep 292006: Oct 62007: Sep 152008: Oct 32009: Sep 302010: Sep 262012: Sep 192013: Sep 132014: Oct 52015: Oct 22016: Oct 92018: Sep 292019: Oct 82020: Sep 172021: Oct 212022: Sep 282023: Oct 172024: Oct 42025: Oct 8

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 19Oct 8May 9Oct 24
2024May 10Oct 4Apr 26Oct 16
2023May 25Oct 17May 25Oct 28
2022May 24Sep 28May 5Oct 14
2021May 29Oct 21Apr 27Oct 21
2020no dataSep 17no dataOct 16
2019May 21Oct 8May 11Oct 25
2018May 20Sep 29May 11Oct 12
2017May 20no dataMay 8no data
2016no dataOct 9no dataNov 12
2015Jun 1Oct 2May 1Oct 14
2014May 17Oct 5May 17Oct 8
2013Jun 3Sep 13May 13Oct 23
2012May 17Sep 19Apr 30Oct 7
2011May 27no dataMay 3no data
2010May 16Sep 26May 10Oct 4
2009no dataSep 30no dataSep 30
2008May 28Oct 3May 9Oct 4
2007May 21Sep 15May 3Sep 15
2006May 23Oct 6May 7Oct 10
2005May 17Sep 29May 17Oct 20
2004May 29Sep 29May 8Oct 2
2003May 22Sep 29May 3Oct 2
2002May 26Sep 23May 21Oct 3
2001May 13Sep 25Apr 19Oct 7
2000May 20Sep 24Apr 30Sep 27
1999May 9Sep 21Apr 24Oct 3
1998Jun 3Oct 1Jun 3Oct 20
1997May 23Oct 1May 6Oct 1
1996no dataSep 29no dataOct 3
1995May 15no dataApr 30no data
1994no dataOct 3no dataOct 9
1976no dataSep 2no dataSep 22
1971Jun 1no dataApr 30no data
1970May 28Sep 28May 6Oct 4
1969May 26Sep 24May 25Oct 14
1968May 10Oct 5May 10Oct 5
1967May 22Sep 10May 22Sep 29
1966May 14Sep 26May 14Oct 12
1965May 29Sep 24Apr 28Sep 26
1964Jun 5Sep 15Jun 1Sep 28
1963May 24Sep 13May 23Nov 14
1962May 9no dataMay 9no 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.