When to plant in Thompson Falls, MT
Planting dates worked out from Thompson Falls's own frost records, not a generic zone chart.
Safe to plant out
May 16
1 year in 10 has a later frost
Average last frost
May 8
about a 50% chance of a later one
Average first fall frost
Oct 2
1 year in 10 by Sep 22
Frost-free days
150
median, 1991–2020
Station used: Thompson Falls Ph · 1.6 km away · station 725 m, town 779 m. How we match towns to stations
This season
Plan your garden.
Planting dates for common crops
| Crop | Start indoors | Plant out or sow | Harvest from |
|---|---|---|---|
| Tomato | Mar 21 – Apr 4 | May 16 – May 30 | Jul 10 |
| Sweet pepper | Mar 7 – Mar 21 | May 16 – May 30 | Jul 15 |
| Lettuce (leaf) | Mar 6 – Mar 13 | Apr 10 – Apr 24 | May 20 |
| Peas | — | Mar 27 – Apr 24 | May 21 |
| Bush beans | — | May 9 – May 30 | Jun 28 |
| Carrot | — | Apr 17 – May 29 | Jun 16 |
| Beet | — | Apr 12 – May 24 | Jun 1 |
| Potato | — | Apr 17 – May 8 | Jun 26 |
| Kale | Feb 27 – Mar 13 | Apr 10 – Apr 24 | May 23 |
| Broccoli | Feb 27 – Mar 13 | Apr 10 – May 1 | Jun 9 |
| Cucumber | Apr 18 – Apr 25 | May 16 – May 30 | Jul 5 |
| Summer squash and zucchini | Apr 18 – Apr 25 | May 16 – May 30 | Jun 30 |
| Winter squash | Apr 18 – Apr 25 | May 16 – May 30 | Aug 4 |
| Sweet corn | — | May 9 – May 30 | Jul 8 |
| Onion (from sets) | — | Apr 10 – May 1 | Jul 9 |
| Garlic | — | Sep 18 – Oct 16 (fall) | following summer |
| Spinach | — | Mar 27 – Apr 24 | May 4 |
| Basil | Apr 4 – Apr 18 | May 16 – May 30 | Jul 12 |
Thompson Falls'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 |
|---|---|
| 1956 | May 13 |
| 1957 | Apr 27 |
| 1958 | Apr 29 |
| 1959 | May 23 |
| 1960 | May 24 |
| 1961 | May 5 |
| 1962 | May 30 |
| 1963 | May 11 |
| 1964 | May 26 |
| 1965 | May 21 |
| 1966 | May 23 |
| 1967 | May 26 |
| 1968 | May 31 |
| 1969 | May 4 |
| 1970 | May 14 |
| 1971 | May 22 |
| 1972 | May 3 |
| 1973 | May 27 |
| 1974 | May 17 |
| 1975 | May 26 |
| 1976 | May 21 |
| 1977 | May 16 |
| 1978 | May 23 |
| 1979 | Apr 21 |
| 1980 | Apr 16 |
| 1981 | May 5 |
| 1982 | May 11 |
| 1983 | May 14 |
| 1984 | May 22 |
| 1985 | May 13 |
| 1986 | May 23 |
| 1987 | May 19 |
| 1988 | May 18 |
| 1989 | May 21 |
| 1990 | May 10 |
| 1991 | May 4 |
| 1992 | May 12 |
| 1993 | Apr 22 |
| 1994 | Apr 29 |
| 1995 | May 4 |
| 1996 | May 21 |
| 1997 | May 8 |
| 1998 | May 16 |
| 1999 | Jun 10 |
| 2000 | May 13 |
| 2001 | May 7 |
| 2002 | May 15 |
| 2003 | May 20 |
| 2004 | May 13 |
| 2005 | May 1 |
| 2006 | May 13 |
| 2007 | May 6 |
| 2008 | May 3 |
| 2009 | May 1 |
| 2010 | May 10 |
| 2011 | May 4 |
| 2012 | May 12 |
| 2013 | May 3 |
| 2014 | May 13 |
| 2015 | May 9 |
| 2016 | Apr 16 |
| 2017 | May 15 |
| 2018 | Apr 24 |
| 2019 | May 1 |
| 2020 | May 4 |
| 2021 | May 9 |
| 2022 | May 11 |
| 2023 | Apr 23 |
| 2024 | May 2 |
| 2025 | May 6 |
| 2026 | Apr 26 |
Each year's frost-free daysLong-term trend
See the data as a table
| Year | Frost-free days |
|---|---|
| 1956 | 131 |
| 1957 | 144 |
| 1958 | 149 |
| 1959 | 130 |
| 1960 | 106 |
| 1961 | 129 |
| 1962 | 100 |
| 1963 | 160 |
| 1964 | 107 |
| 1965 | 100 |
| 1966 | 132 |
| 1967 | 141 |
| 1968 | 123 |
| 1969 | 133 |
| 1970 | 121 |
| 1971 | 114 |
| 1972 | 145 |
| 1973 | 111 |
| 1974 | 118 |
| 1975 | 115 |
| 1976 | 109 |
| 1977 | 139 |
| 1978 | 116 |
| 1979 | 164 |
| 1980 | 176 |
| 1981 | 140 |
| 1982 | 126 |
| 1983 | 127 |
| 1984 | 113 |
| 1985 | 131 |
| 1986 | 111 |
| 1987 | 120 |
| 1988 | 116 |
| 1989 | 112 |
| 1990 | 148 |
| 1991 | 140 |
| 1992 | 117 |
| 1993 | 152 |
| 1994 | 161 |
| 1995 | 139 |
| 1996 | 124 |
| 1997 | 152 |
| 1998 | 140 |
| 1999 | 108 |
| 2000 | 131 |
| 2001 | 149 |
| 2003 | 143 |
| 2004 | 150 |
| 2005 | 145 |
| 2006 | 148 |
| 2007 | 160 |
| 2008 | 158 |
| 2009 | 157 |
| 2010 | 154 |
| 2011 | 165 |
| 2012 | 144 |
| 2013 | 153 |
| 2014 | 121 |
| 2015 | 141 |
| 2016 | 168 |
| 2018 | 161 |
| 2019 | 150 |
| 2020 | 170 |
| 2021 | 150 |
| 2022 | 175 |
| 2023 | 171 |
| 2024 | 153 |
| 2025 | 152 |
Each year's average temperature, April to SeptemberLong-term trend
See the data as a table
| Year | Growing-season temperature |
|---|---|
| 1956 | 15.5 °C |
| 1957 | 15.6 °C |
| 1958 | 16.6 °C |
| 1959 | 14.4 °C |
| 1960 | 15.1 °C |
| 1961 | 15.7 °C |
| 1962 | 14.5 °C |
| 1963 | 15.6 °C |
| 1964 | 13.9 °C |
| 1965 | 14.4 °C |
| 1966 | 15.9 °C |
| 1967 | 16.3 °C |
| 1968 | 14.6 °C |
| 1969 | 15.5 °C |
| 1970 | 15.2 °C |
| 1971 | 15.3 °C |
| 1972 | 14.9 °C |
| 1973 | 15.9 °C |
| 1974 | 15.5 °C |
| 1975 | 14.7 °C |
| 1976 | 15.4 °C |
| 1977 | 15.7 °C |
| 1978 | 15.0 °C |
| 1979 | 16.4 °C |
| 1980 | 15.5 °C |
| 1981 | 15.5 °C |
| 1982 | 14.9 °C |
| 1983 | 15.0 °C |
| 1984 | 15.3 °C |
| 1989 | 16.2 °C |
| 1990 | 16.9 °C |
| 1991 | 16.1 °C |
| 1995 | 15.7 °C |
| 1996 | 15.1 °C |
| 1998 | 17.5 °C |
| 2000 | 15.3 °C |
| 2001 | 16.7 °C |
| 2003 | 17.2 °C |
| 2004 | 16.1 °C |
| 2005 | 16.3 °C |
| 2006 | 17.3 °C |
| 2007 | 17.3 °C |
| 2008 | 15.4 °C |
| 2009 | 16.9 °C |
| 2010 | 15.1 °C |
| 2011 | 14.9 °C |
| 2012 | 16.2 °C |
| 2013 | 16.3 °C |
| 2015 | 17.0 °C |
| 2016 | 16.4 °C |
| 2017 | 16.4 °C |
| 2018 | 16.3 °C |
| 2019 | 15.5 °C |
| 2020 | 15.7 °C |
| 2021 | 16.6 °C |
| 2022 | 15.3 °C |
| 2023 | 16.8 °C |
| 2024 | 16.4 °C |
| 2025 | 17.1 °C |
| 2026 | 16.1 °C |
What this means for you: Since 1956, Thompson Falls's last spring frost has come about 2 days earlier per decade, on average. The frost-free season has grown by about 5 days per decade. Year-to-year swings are large, so keep using the safe date rather than the trend.
Source: daily records from Thompson Falls Ph (NOAA GHCN-Daily). Years with too many missing days are left out.