Last Frost Day

Frost history / Boise Lucky Peak Dam, ID

Boise Lucky Peak Dam, ID: frost dates by year

Last spring and first fall frost at NOAA station USC00101018, 1957 to 2025, measured from daily minimum temperatures.

Elevation 2,840 ft, 43.525, -116.054. Download the data (JSON), NOAA daily records

Summary at 32°F

Last spring frostFirst fall frost
MedianMay 2Oct 15
EarliestApr 4 (1989)Sep 13 (1970)
LatestJun 4 (1962)Nov 16 (2016)
Trend2.1 days earlier per decade2.3 days later per decade
Years with data3740

At 28°F (hard freeze) the median last spring date is Apr 12 and the median first fall date is Oct 29.

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 16Mar 31Apr 15Apr 30May 15May 30Jun 1419601970198019902000201020201958: Apr 271959: May 191960: May 181961: May 141962: Jun 41963: Apr 281965: May 61970: May 121971: May 181972: May 11973: Apr 301974: May 191975: May 241976: Apr 191977: May 171978: May 61979: May 311980: Apr 131981: May 81983: Apr 131986: May 151987: Apr 121988: May 41989: Apr 42010: May 122013: May 22015: Apr 262016: Apr 162017: Apr 282018: May 12019: May 12020: Apr 132021: Apr 202022: May 92023: Apr 252024: Apr 302025: May 19

First fall frost (32°F)

Aug 28Sep 12Sep 27Oct 12Oct 27Nov 11Nov 2619601970198019902000201020201957: Oct 201958: Sep 241959: Oct 261960: Oct 91961: Oct 71962: Oct 161963: Oct 261970: Sep 131971: Oct 151972: Sep 251973: Oct 31974: Oct 41975: Oct 231976: Oct 41977: Oct 101978: Oct 221980: Oct 221981: Oct 241982: Oct 51984: Sep 241985: Oct 81986: Oct 21987: Oct 191988: Sep 182009: Oct 42010: Nov 82011: Oct 242012: Oct 52014: Nov 112015: Nov 22016: Nov 162017: Oct 92018: Oct 142019: Oct 92020: Oct 212021: Oct 112022: Oct 222023: Oct 272024: Oct 182025: Oct 27

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 27Apr 13Nov 30
2024Apr 30Oct 18Apr 29Oct 18
2023Apr 25Oct 27Apr 19Oct 27
2022May 9Oct 22Apr 9Nov 2
2021Apr 20Oct 11Apr 12Oct 13
2020Apr 13Oct 21Apr 12Oct 21
2019May 1Oct 9Mar 15Oct 9
2018May 1Oct 14Apr 17Nov 5
2017Apr 28Oct 9Apr 9Oct 12
2016Apr 16Nov 16Mar 28Nov 16
2015Apr 26Nov 2Apr 16Nov 3
2014no dataNov 11no dataNov 11
2013May 2no dataMay 2no data
2012no dataOct 5no dataNov 9
2011no dataOct 24no dataOct 24
2010May 12Nov 8Apr 9Nov 8
2009no dataOct 4no dataOct 5
1989Apr 4no dataMar 30no data
1988May 4Sep 18Apr 9Oct 27
1987Apr 12Oct 19Apr 10Oct 19
1986May 15Oct 2Mar 18Nov 7
1985no dataOct 8no dataOct 8
1984no dataSep 24no dataOct 16
1983Apr 13no dataApr 12no data
1982no dataOct 5no dataNov 2
1981May 8Oct 24Apr 13Nov 25
1980Apr 13Oct 22Apr 12Oct 22
1979May 31no dataApr 3no data
1978May 6Oct 22Mar 16Oct 22
1977May 17Oct 10Apr 20Nov 8
1976Apr 19Oct 4Apr 19Nov 15
1975May 24Oct 23Apr 19Oct 23
1974May 19Oct 4Apr 14Oct 5
1973Apr 30Oct 3Apr 3Nov 2
1972May 1Sep 25May 1Oct 29
1971May 18Oct 15Apr 3Oct 25
1970May 12Sep 13Apr 29Oct 8
1965May 6no dataMay 6no data
1963Apr 28Oct 26Apr 21Nov 21
1962Jun 4Oct 16Apr 10Nov 7
1961May 14Oct 7Apr 6Oct 8
1960May 18Oct 9Apr 16Nov 4
1959May 19Oct 26May 4Oct 30
1958Apr 27Sep 24Mar 16Nov 11
1957no dataOct 20no dataNov 1

"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.