When to plant in Rio, WI
Planting dates worked out from Rio's own frost records, not a generic zone chart.
Safe to plant out
May 26
1 year in 10 has a later frost
Average last frost
May 9
about a 50% chance of a later one
Average first fall frost
Oct 2
1 year in 10 by Sep 19
Frost-free days
142
median, 1991–2020
Station used: Arlington · 18.1 km away · station 321 m, town 284 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 31 – Apr 14 | May 26 – Jun 9 | Jul 20 |
| Sweet pepper | Mar 17 – Mar 31 | May 26 – Jun 9 | Jul 25 |
| Lettuce (leaf) | Mar 7 – Mar 14 | Apr 11 – Apr 25 | May 21 |
| Peas | — | Apr 10 – May 8 | Jun 4 |
| Bush beans | — | May 19 – Jun 9 | Jul 8 |
| Carrot | — | Apr 20 – Jun 1 | Jun 19 |
| Beet | — | Apr 20 – Jun 1 | Jun 9 |
| Potato | — | Apr 20 – May 11 | Jun 29 |
| Kale | Mar 6 – Mar 20 | Apr 17 – May 1 | May 30 |
| Broccoli | Feb 28 – Mar 14 | Apr 11 – May 2 | Jun 10 |
| Cucumber | Apr 28 – May 5 | May 26 – Jun 9 | Jul 15 |
| Summer squash and zucchini | Apr 28 – May 5 | May 26 – Jun 9 | Jul 10 |
| Winter squash | Apr 28 – May 5 | May 26 – Jun 9 | Aug 14 |
| Sweet corn | — | May 19 – Jun 9 | Jul 18 |
| Onion (from sets) | — | Apr 11 – May 2 | Jul 10 |
| Garlic | — | Sep 18 – Oct 16 (fall) | following summer |
| Spinach | — | Apr 10 – May 8 | May 18 |
| Basil | Apr 14 – Apr 28 | May 26 – Jun 9 | Jul 22 |
Rio'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 |
|---|---|
| 1963 | May 23 |
| 1964 | Apr 25 |
| 1965 | May 29 |
| 1966 | May 11 |
| 1967 | May 22 |
| 1968 | May 6 |
| 1969 | Apr 30 |
| 1970 | May 7 |
| 1971 | May 12 |
| 1972 | Apr 26 |
| 1973 | Apr 28 |
| 1974 | May 7 |
| 1975 | Apr 22 |
| 1976 | May 8 |
| 1977 | May 10 |
| 1978 | May 6 |
| 1979 | May 1 |
| 1980 | May 9 |
| 1981 | May 12 |
| 1982 | Apr 28 |
| 1983 | May 10 |
| 1984 | Apr 23 |
| 1985 | Apr 10 |
| 1986 | May 3 |
| 1987 | Apr 30 |
| 1988 | May 25 |
| 1989 | May 7 |
| 1990 | May 11 |
| 1991 | May 3 |
| 1992 | May 25 |
| 1993 | May 13 |
| 1994 | May 27 |
| 1995 | Apr 25 |
| 1996 | May 13 |
| 1998 | Apr 27 |
| 1999 | Apr 23 |
| 2000 | Apr 20 |
| 2001 | Apr 17 |
| 2002 | May 20 |
| 2003 | May 2 |
| 2004 | May 2 |
| 2006 | May 20 |
| 2007 | Apr 15 |
| 2008 | May 28 |
| 2009 | May 17 |
| 2010 | May 10 |
| 2011 | May 27 |
| 2012 | Apr 29 |
| 2013 | May 24 |
| 2014 | May 17 |
| 2015 | May 13 |
| 2016 | May 16 |
| 2017 | May 8 |
| 2018 | Apr 28 |
| 2019 | Apr 28 |
| 2020 | May 13 |
| 2021 | May 30 |
| 2022 | May 4 |
| 2023 | May 3 |
| 2024 | Apr 26 |
| 2025 | May 9 |
Each year's frost-free daysLong-term trend
See the data as a table
| Year | Frost-free days |
|---|---|
| 1963 | 158 |
| 1964 | 155 |
| 1965 | 119 |
| 1966 | 143 |
| 1967 | 128 |
| 1968 | 150 |
| 1969 | 166 |
| 1970 | 161 |
| 1971 | 152 |
| 1972 | 156 |
| 1973 | 188 |
| 1974 | 137 |
| 1975 | 162 |
| 1976 | 136 |
| 1977 | 153 |
| 1978 | 154 |
| 1979 | 156 |
| 1980 | 146 |
| 1981 | 142 |
| 1982 | 170 |
| 1983 | 135 |
| 1984 | 155 |
| 1985 | 178 |
| 1986 | 155 |
| 1987 | 155 |
| 1989 | 139 |
| 1990 | 151 |
| 1991 | 139 |
| 1992 | 120 |
| 1993 | 120 |
| 1994 | 135 |
| 1995 | 150 |
| 1996 | 142 |
| 1999 | 161 |
| 2000 | 167 |
| 2001 | 170 |
| 2002 | 138 |
| 2003 | 150 |
| 2004 | 151 |
| 2006 | 137 |
| 2007 | 151 |
| 2008 | 126 |
| 2009 | 135 |
| 2010 | 139 |
| 2011 | 110 |
| 2012 | 145 |
| 2013 | 142 |
| 2014 | 140 |
| 2015 | 156 |
| 2016 | 149 |
| 2017 | 160 |
| 2018 | 153 |
| 2019 | 166 |
| 2020 | 141 |
| 2021 | 144 |
| 2022 | 147 |
| 2023 | 158 |
| 2024 | 171 |
| 2025 | 167 |
Each year's average temperature, April to SeptemberLong-term trend
See the data as a table
| Year | Growing-season temperature |
|---|---|
| 1963 | 16.7 °C |
| 1964 | 16.5 °C |
| 1965 | 16.1 °C |
| 1966 | 15.5 °C |
| 1967 | 15.5 °C |
| 1968 | 16.4 °C |
| 1969 | 16.3 °C |
| 1970 | 17.4 °C |
| 1971 | 16.9 °C |
| 1972 | 16.5 °C |
| 1973 | 16.7 °C |
| 1974 | 16.0 °C |
| 1975 | 16.4 °C |
| 1976 | 17.0 °C |
| 1977 | 18.0 °C |
| 1978 | 17.0 °C |
| 1979 | 15.9 °C |
| 1980 | 17.2 °C |
| 1981 | 16.6 °C |
| 1982 | 16.1 °C |
| 1983 | 16.8 °C |
| 1984 | 16.6 °C |
| 1986 | 16.8 °C |
| 1987 | 18.1 °C |
| 1988 | 18.9 °C |
| 1989 | 16.7 °C |
| 1990 | 17.0 °C |
| 1991 | 17.7 °C |
| 1992 | 15.0 °C |
| 1993 | 15.2 °C |
| 1994 | 16.2 °C |
| 1995 | 17.7 °C |
| 1996 | 16.4 °C |
| 1998 | 17.8 °C |
| 1999 | 17.1 °C |
| 2000 | 16.9 °C |
| 2001 | 17.2 °C |
| 2002 | 17.2 °C |
| 2003 | 16.3 °C |
| 2004 | 16.1 °C |
| 2006 | 16.8 °C |
| 2007 | 16.8 °C |
| 2008 | 15.7 °C |
| 2009 | 14.6 °C |
| 2010 | 16.6 °C |
| 2011 | 15.3 °C |
| 2012 | 16.6 °C |
| 2013 | 15.1 °C |
| 2014 | 15.2 °C |
| 2015 | 16.8 °C |
| 2016 | 17.2 °C |
| 2017 | 16.6 °C |
| 2018 | 16.9 °C |
| 2019 | 16.5 °C |
| 2020 | 16.6 °C |
| 2021 | 17.6 °C |
| 2022 | 16.6 °C |
| 2023 | 17.4 °C |
| 2024 | 17.7 °C |
| 2025 | 16.7 °C |
What this means for you: Since 1963, Rio's last spring frost has stayed at about the same time of year. Year-to-year swings are large, so keep using the safe date rather than the trend.
Source: daily records from Arlington (NOAA GHCN-Daily). Years with too many missing days are left out.