Last Frost Day

Frost history / Duluth Harbor Stn, MN

Duluth Harbor Stn, MN: frost dates by year

Last spring and first fall frost at NOAA station USC00212246, 1960 to 2004, measured from daily minimum temperatures.

Elevation 610 ft, 46.768, -92.090. Download the data (JSON), NOAA daily records

Summary at 32°F

Last spring frostFirst fall frost
MedianMay 1Oct 19
EarliestApr 5 (1987)Sep 19 (2003)
LatestJun 4 (2002)Nov 12 (1975)
Trend1.6 days later per decade2.5 days earlier per decade
Years with data3539

At 28°F (hard freeze) the median last spring date is Apr 21 and the median first fall date is Nov 2.

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)

Mar 31Apr 15Apr 30May 15May 30Jun 14196019701980199020001961: May 101962: Apr 281963: May 121964: Apr 201965: Apr 281966: May 101967: May 121968: Apr 251969: Apr 291970: Apr 221971: Apr 301972: May 161973: Apr 221974: May 131975: May 21976: Apr 271977: May 111978: Apr 211979: May 81981: May 151983: Apr 191984: May 21985: Apr 171986: Apr 221987: Apr 51989: May 71992: Apr 271993: Apr 261995: May 11996: May 121997: May 131999: Apr 302002: Jun 42003: May 12004: May 22

First fall frost (32°F)

Sep 12Sep 27Oct 12Oct 27Nov 11Nov 26196019701980199020001960: Oct 191961: Sep 281962: Oct 231963: Nov 11964: Oct 91965: Sep 261966: Oct 161967: Oct 271968: Nov 71969: Oct 221970: Nov 71971: Oct 301972: Oct 161973: Nov 31974: Sep 231975: Nov 121976: Sep 221977: Nov 101978: Nov 101979: Oct 121980: Oct 281981: Oct 21982: Nov 31983: Nov 41984: Oct 281985: Oct 101986: Oct 311989: Oct 31990: Oct 191991: Oct 151994: Oct 311996: Oct 111997: Oct 181998: Oct 231999: Oct 32000: Oct 62001: Oct 62002: Oct 132003: Sep 19

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
2004May 22no dataMay 22no data
2003May 1Sep 19Apr 24Oct 1
2002Jun 4Oct 13May 19Oct 16
2001no dataOct 6no dataOct 19
2000no dataOct 6no dataNov 15
1999Apr 30Oct 3Mar 27Oct 4
1998no dataOct 23no dataNov 4
1997May 13Oct 18Apr 18Nov 11
1996May 12Oct 11May 8Oct 30
1995May 1no dataApr 12no data
1994no dataOct 31no dataNov 19
1993Apr 26no dataApr 14no data
1992Apr 27no dataApr 14no data
1991no dataOct 15no dataOct 20
1990no dataOct 19no dataNov 5
1989May 7Oct 3May 6Oct 19
1987Apr 5no dataApr 3no data
1986Apr 22Oct 31Apr 22Nov 1
1985Apr 17Oct 10Apr 9Oct 10
1984May 2Oct 28Apr 23Oct 29
1983Apr 19Nov 4Apr 18Nov 10
1982no dataNov 3no dataNov 4
1981May 15Oct 2May 10Oct 22
1980no dataOct 28no dataNov 9
1979May 8Oct 12May 1Nov 2
1978Apr 21Nov 10Apr 21Nov 11
1977May 11Nov 10May 7Nov 10
1976Apr 27Sep 22Apr 4Oct 22
1975May 2Nov 12Apr 21Nov 14
1974May 13Sep 23Apr 24Nov 12
1973Apr 22Nov 3Apr 22Nov 3
1972May 16Oct 16May 5Oct 17
1971Apr 30Oct 30Apr 13Nov 5
1970Apr 22Nov 7Apr 10Nov 13
1969Apr 29Oct 22Apr 6Nov 13
1968Apr 25Nov 7Apr 6Nov 10
1967May 12Oct 27May 3Nov 3
1966May 10Oct 16May 9Nov 1
1965Apr 28Sep 26Apr 28Oct 24
1964Apr 20Oct 9Apr 14Nov 18
1963May 12Nov 1Apr 18Nov 2
1962Apr 28Oct 23Apr 16Oct 25
1961May 10Sep 28Apr 16Oct 29
1960no dataOct 19no dataOct 19

"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.