When to plant in Dillon, MT

Planting dates worked out from Dillon's own frost records, not a generic zone chart.

Safe to plant out

Jun 16

1 year in 10 has a later frost

Average last frost

Jun 4

about a 50% chance of a later one

Average first fall frost

Sep 12

1 year in 10 by Aug 30

Frost-free days

median, 1991–2020

Station used: Dillon U Of Montana Western · 0.8 km away · station 1563 m, town 1555 m. How we match towns to stations

This season

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Planting dates for common crops

Crop	Start indoors	Plant out or sow	Harvest from
Tomato	Apr 21 – May 5	Jun 16 – Jun 30	Aug 10
Sweet pepper	Apr 7 – Apr 21	Jun 16 – Jun 30	Aug 15
Lettuce (leaf)	Apr 2 – Apr 9	May 7 – May 21	Jun 16
Peas	—	Apr 23 – May 21	Jun 17
Bush beans	—	Jun 9 – Jun 30	Jul 29
Carrot	—	May 14 – Jun 25	Jul 13
Beet	—	May 7 – Jun 18	Jun 26
Potato	—	May 14 – Jun 4	Jul 23
Kale	Mar 26 – Apr 9	May 7 – May 21	Jun 19
Broccoli	Mar 26 – Apr 9	May 7 – May 28	Jul 6
Cucumber	May 19 – May 26	Jun 16 – Jun 30	Aug 5
Summer squash and zucchini	May 19 – May 26	Jun 16 – Jun 30	Jul 31
Winter squash Season likely too short	May 19 – May 26	Jun 16 – Jun 30	Sep 4
Sweet corn	—	Jun 9 – Jun 30	Aug 8
Onion (from sets)	—	May 7 – May 28	Aug 5
Garlic	—	Aug 29 – Sep 26 (fall)	following summer
Spinach	—	Apr 23 – May 21	May 31
Basil	May 5 – May 19	Jun 16 – Jun 30	Aug 12

Plan all 65 crops for Dillon

Dillon's weather over time

How the growing season has shifted here, year by year, from the station's own records.

Each year's last spring frostLong-term trend

See the data as a table

Year	Last spring frost
1896	Jun 11
1900	Jul 7
1901	Jun 14
1902	Jun 17
1903	May 24
1904	Jul 14
1905	Jun 21
1906	May 29
1907	May 22
1908	Jun 28
1909	May 14
1910	May 16
1911	Jun 5
1912	May 4
1913	Jul 13
1914	Jun 22
1915	Jun 26
1916	Jun 12
1917	May 16
1918	Jul 3
1919	Jun 10
1920	Jul 6
1921	May 12
1922	Jun 1
1923	Jun 14
1924	Jun 8
1925	Apr 28
1926	May 12
1927	May 18
1928	May 3
1929	Jun 4
1930	May 23
1931	May 19
1932	Apr 25
1933	May 11
1934	Jun 2
1935	Jul 1
1936	May 22
1937	Jun 25
1938	Jun 11
1939	Jun 2
1940	Jun 23
1941	May 28
1942	Jun 22
1943	Jun 6
1944	May 25
1945	Jun 15
1946	Jun 19
1947	Jun 30
1948	May 15
1949	Jun 30
1950	Jun 8
1951	Jun 30
1952	Jul 7
1953	Jun 26
1954	Jun 18
1955	Jul 2
1956	May 14
1957	May 24
1958	May 14
1959	Jun 10
1960	Jun 21
1961	May 20
1962	Jun 7
1963	Jun 22
1964	May 26
1965	May 18
1966	Jun 5
1967	May 26
1968	Jun 14
1969	Jun 14
1970	May 14
1971	May 24
1972	May 26
1973	Jun 19
1974	May 31
1975	Jun 28
1976	May 21
1977	Jul 7
1978	Jun 17
1979	Jun 9
1980	May 25
1981	Jul 8
1982	May 31
1983	May 31
1984	Jun 2
1985	Jun 26
1986	May 24
1987	Jun 3
1988	Jul 7
1989	May 31
1990	Jun 1
1991	Jun 18
1992	May 12
1993	Jun 13
1994	Jun 15
1995	Jun 7
1996	May 21
1997	May 19
1998	Jun 5
1999	Jun 11
2000	Jun 1
2001	Jun 16
2002	Jun 11
2003	Jun 23
2004	Jun 16
2005	May 30
2006	May 13
2007	Jun 26
2008	Jun 11
2009	May 21
2010	May 29
2011	Jun 4
2012	Jun 11
2013	Jun 1
2014	May 30
2015	May 11
2016	May 31
2017	Jun 11
2018	Jun 12
2019	May 13
2020	Jun 9
2022	Jun 25
2023	Jun 22
2024	May 25
2025	May 19

Each year's frost-free daysLong-term trend

See the data as a table

Year	Frost-free days
1900	56
1901	88
1902	53
1903	95
1904	0
1905	87
1906	88
1907	88
1908	58
1909	105
1910	93
1911	58
1912	125
1913	16
1914	49
1915	75
1916	65
1917	112
1918	41
1919	103
1920	42
1921	114
1922	98
1923	95
1924	104
1925	144
1926	122
1927	119
1928	139
1929	91
1930	100
1931	125
1932	127
1933	130
1934	98
1935	85
1937	64
1938	124
1939	65
1940	98
1941	107
1942	70
1943	91
1944	115
1945	83
1946	49
1947	69
1948	112
1949	27
1950	94
1951	61
1952	68
1953	69
1954	91
1955	69
1956	108
1957	107
1958	111
1959	83
1960	67
1961	115
1962	87
1963	115
1964	100
1965	102
1966	76
1967	109
1968	80
1969	81
1970	120
1971	113
1972	103
1973	86
1974	93
1975	66
1976	109
1977	51
1978	91
1979	93
1980	95
1981	74
1982	102
1983	101
1984	102
1985	84
1986	105
1987	105
1988	71
1989	98
1990	123
1991	91
1992	104
1993	77
1994	98
1995	105
1996	107
1997	122
1998	107
1999	88
2000	110
2001	83
2002	66
2003	82
2004	79
2005	104
2006	109
2007	83
2008	88
2009	122
2010	135
2011	48
2012	92
2013	117
2014	96
2015	117
2016	126
2017	95
2018	96
2019	137
2020	90
2022	75
2023	97
2024	130
2025	138

Each year's average temperature, April to SeptemberLong-term trend

See the data as a table

Year	Growing-season temperature
1900	13.8 °C
1901	15.1 °C
1902	11.8 °C
1903	11.8 °C
1904	12.7 °C
1905	12.9 °C
1906	13.6 °C
1907	12.7 °C
1908	12.9 °C
1909	13.8 °C
1910	14.0 °C
1911	13.1 °C
1912	13.1 °C
1913	11.5 °C
1914	13.1 °C
1915	11.9 °C
1916	11.6 °C
1917	12.6 °C
1918	11.8 °C
1919	14.0 °C
1920	11.4 °C
1921	12.4 °C
1922	12.5 °C
1923	12.4 °C
1924	13.1 °C
1925	14.1 °C
1926	13.5 °C
1927	13.6 °C
1928	14.1 °C
1929	14.0 °C
1930	15.6 °C
1931	15.6 °C
1932	14.7 °C
1933	14.9 °C
1934	16.1 °C
1935	12.2 °C
1937	13.4 °C
1938	13.7 °C
1939	13.6 °C
1940	14.6 °C
1941	12.8 °C
1942	12.7 °C
1943	13.4 °C
1944	12.8 °C
1945	12.5 °C
1946	13.0 °C
1947	13.2 °C
1948	13.4 °C
1949	14.4 °C
1950	11.9 °C
1951	12.1 °C
1952	13.9 °C
1953	12.9 °C
1954	13.2 °C
1955	12.6 °C
1956	13.4 °C
1957	13.4 °C
1958	14.0 °C
1959	13.0 °C
1960	13.3 °C
1961	13.7 °C
1962	13.1 °C
1963	13.3 °C
1964	12.6 °C
1965	11.8 °C
1966	13.9 °C
1967	13.3 °C
1968	12.4 °C
1969	14.3 °C
1970	13.6 °C
1972	13.3 °C
1973	13.4 °C
1974	13.9 °C
1975	12.4 °C
1977	13.4 °C
1978	13.2 °C
1979	13.8 °C
1980	13.7 °C
1981	14.0 °C
1982	12.6 °C
1983	12.9 °C
1984	13.0 °C
1985	13.9 °C
1986	13.6 °C
1987	14.3 °C
1989	14.2 °C
1991	14.2 °C
1992	14.6 °C
1993	12.6 °C
1996	14.2 °C
2010	12.7 °C
2011	13.1 °C
2012	14.9 °C
2013	14.5 °C
2014	13.6 °C
2015	14.2 °C
2016	13.8 °C
2017	13.9 °C
2018	13.7 °C
2019	13.2 °C
2020	13.9 °C
2023	13.5 °C
2024	14.6 °C
2025	14.1 °C

What this means for you: Since 1896, Dillon's last spring frost has stayed at about the same time of year. The frost-free season has grown by about 2 days per decade. Year-to-year swings are large, so keep using the safe date rather than the trend.

Source: daily records from Dillon U Of Montana Western (NOAA GHCN-Daily). Years with too many missing days are left out.

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