When Is the Last Frost in South Dakota?
The average last spring frost in South Dakota falls between May 1 and May 14 for most ZIP codes, with a statewide median of May 6. At the average date a later frost is still a coin flip, so tender plants wait for the safer 90% date.
| City | Last frost | 90% safe after | First frost | Growing season |
|---|---|---|---|---|
| Sioux Falls | Apr 26 | May 9 | Oct 13 | 169 days |
| Rapid City | May 3 | May 17 | Oct 8 | 157 days |
| Aberdeen | May 8 | May 21 | Sep 29 | 144 days |
| Brookings | May 6 | May 19 | Oct 1 | 145 days |
| Watertown | May 7 | May 20 | Sep 30 | 145 days |
| Yankton | Apr 27 | May 10 | Oct 11 | 164 days |
| Mitchell | May 2 | May 15 | Oct 6 | 156 days |
| Huron | May 6 | May 20 | Oct 2 | 146 days |
| Box Elder | May 3 | May 17 | Oct 8 | 157 days |
| Spearfish | May 12 | May 25 | Oct 2 | 143 days |
| Pierre | May 6 | May 19 | Oct 5 | 152 days |
| Vermillion | May 3 | May 16 | Oct 3 | 153 days |
| Sturgis | May 8 | May 21 | Oct 3 | 147 days |
| Madison | May 5 | May 18 | Sep 30 | 148 days |
| Dell Rapids | May 1 | May 15 | Oct 4 | 155 days |
| Hot Springs | May 16 | May 31 | Sep 27 | 133 days |
| Milbank | May 5 | May 18 | Oct 2 | 150 days |
| Mobridge | May 5 | May 20 | Oct 4 | 150 days |
Last and first frost: 50% (median) dates of the last spring and first fall 32 °F night. 90% safe after: only a 10% chance of a later spring frost. First frost dates in January fall in the following winter. Each city uses the NOAA station nearest the ZIP code closest to its center.
Across all 166 South Dakota weather stations with frost records, median last frost dates run from April 26 at Sioux Falls WFO AP, SD to June 1 at Hill City, SD. Elevation, valleys that collect cold air and distance from large water bodies explain most of the spread, so a garden a few miles from a listed city can differ by a week or more. The ZIP code lookup above uses the same NOAA data as the frost date calculator for every US ZIP code.
When Is the First Frost in South Dakota?
The average first fall frost in South Dakota arrives between September 28 and October 9 for most ZIP codes, with a median of October 2. Tomatoes, peppers, basil and squash are damaged at 32 °F, so harvest or cover them before then.
Fall frost can come early: Sioux Falls has a 10% chance of frost before September 28, Rapid City has a 10% chance of frost before September 26 and Aberdeen has a 10% chance of frost before September 17. Hardy crops such as kale, spinach and cabbage tolerate light frosts and keep producing after the first frost date.
When to Plant Tomatoes in South Dakota?
Transplant tomatoes in South Dakota 1 to 2 weeks after the local average last frost, once nights stay above about 50 °F: May 3 – May 10 in Sioux Falls, May 10 – May 17 in Rapid City and May 15 – May 22 in Aberdeen. Start seeds indoors 6 to 8 weeks before the last frost.
| City | Start seeds indoors | Transplant outdoors | Lowest-risk transplant |
|---|---|---|---|
| Sioux Falls | Mar 1 – Mar 15 | May 3 – May 10 | after May 9 |
| Rapid City | Mar 8 – Mar 22 | May 10 – May 17 | after May 17 |
| Aberdeen | Mar 13 – Mar 27 | May 15 – May 22 | after May 21 |
| Brookings | Mar 11 – Mar 25 | May 13 – May 20 | after May 19 |
| Watertown | Mar 12 – Mar 26 | May 14 – May 21 | after May 20 |
| Yankton | Mar 2 – Mar 16 | May 4 – May 11 | after May 10 |
| Mitchell | Mar 7 – Mar 21 | May 9 – May 16 | after May 15 |
| Huron | Mar 11 – Mar 25 | May 13 – May 20 | after May 20 |
| Box Elder | Mar 8 – Mar 22 | May 10 – May 17 | after May 17 |
| Spearfish | Mar 17 – Mar 31 | May 19 – May 26 | after May 25 |
| Pierre | Mar 11 – Mar 25 | May 13 – May 20 | after May 19 |
| Vermillion | Mar 8 – Mar 22 | May 10 – May 17 | after May 16 |
| Sturgis | Mar 13 – Mar 27 | May 15 – May 22 | after May 21 |
| Madison | Mar 10 – Mar 24 | May 12 – May 19 | after May 18 |
| Dell Rapids | Mar 6 – Mar 20 | May 8 – May 15 | after May 15 |
| Hot Springs | Mar 21 – Apr 4 | May 23 – May 30 | after May 31 |
| Milbank | Mar 10 – Mar 24 | May 12 – May 19 | after May 18 |
| Mobridge | Mar 10 – Mar 24 | May 12 – May 19 | after May 20 |
Indoors: 6–8 weeks before the average last frost. Outdoors: 1–2 weeks after it. Lowest-risk: after the date with only a 10% chance of a later frost. Rules of thumb; check the 10-day forecast and wait for soil near 60 °F.
Tomatoes stall below about 50 °F at night and are killed by frost, so a week or two of waiting after the average date costs little. The tomato plant care guide covers light, watering and feeding once plants are in the ground.
What Can You Plant in Sioux Falls and When?
Sioux Falls's average last frost of April 26 anchors its spring planting calendar: peas and spinach go in from March 15, broccoli and lettuce transplants from March 29, and tomatoes, peppers and squash after May 3.
| Crop | Start seeds indoors | Plant outdoors | Frost tolerance |
|---|---|---|---|
| Peas | — | Mar 15 – Mar 29direct sow, 4–6 weeks before last frost | hardy |
| Spinach | — | Mar 15 – Apr 5direct sow, 3–6 weeks before last frost | hardy |
| Radishes | — | Mar 22 – Apr 5direct sow, 3–5 weeks before last frost | hardy |
| Onions (sets) | — | Mar 29 – Apr 12plant, 2–4 weeks before last frost | hardy |
| Potatoes | — | Mar 29 – Apr 12plant, 2–4 weeks before last frost | half-hardy |
| Broccoli & cabbage | Mar 1 – Mar 15 | Mar 29 – Apr 12transplant, 2–4 weeks before last frost | hardy |
| Lettuce | Mar 15 – Mar 29 | Mar 29 – Apr 12transplant, 2–4 weeks before last frost | hardy |
| Beets | — | Mar 29 – Apr 12direct sow, 2–4 weeks before last frost | half-hardy |
| Carrots | — | Apr 5 – Apr 12direct sow, 2–3 weeks before last frost | half-hardy |
| Tomatoes | Mar 1 – Mar 15 | May 3 – May 10transplant, 1–2 weeks after last frost | tender |
| Basil | Mar 1 – Mar 15 | May 3 – May 17transplant, 1–3 weeks after last frost | tender |
| Peppers | Feb 15 – Mar 1 | May 10 – May 17transplant, 2–3 weeks after last frost | tender |
| Eggplant | Feb 15 – Mar 1 | May 10 – May 17transplant, 2–3 weeks after last frost | tender |
| Green beans | — | May 3 – May 17direct sow, 1–3 weeks after last frost | tender |
| Sweet corn | — | May 3 – May 17direct sow, 1–3 weeks after last frost | tender |
| Cucumbers | Mar 29 – Apr 5 | May 3 – May 17transplant, 1–3 weeks after last frost | tender |
| Squash & zucchini | Mar 29 – Apr 5 | May 3 – May 17transplant, 1–3 weeks after last frost | tender |
| Watermelon | Mar 29 – Apr 5 | May 10 – May 17transplant, 2–3 weeks after last frost | tender |
Dates for Sioux Falls (last frost Apr 26, NOAA station Sioux Falls WFO AP, SD, 4 miles from ZIP 57117). General rules of thumb; wait for soil near 50 °F for most seeds and 60 °F for beans, corn and squash.
How Long Is the Growing Season in South Dakota?
The frost-free growing season in South Dakota lasts about 136 to 161 days for most ZIP codes, with a median of 148 days. Among the listed cities, Hot Springs has the shortest season at 133 days and Sioux Falls the longest at 169.
Season length decides which varieties ripen: compare it with the “days to maturity” on seed packets, counted from transplanting for tomatoes and peppers. NOAA stations in South Dakota range from 102 days at Hill City, SD to 169 days at Sioux Falls WFO AP, SD. Planning beds before the season starts helps in short seasons — a plant spacing calculator for vegetable beds shows how many transplants fit.
What Hardiness Zones Are in South Dakota?
South Dakota spans USDA hardiness zones 4a to 5b, with zone 4b the most common. Zones describe winter cold and decide which perennials survive, while frost dates set when to plant annual vegetables and flowers.
The South Dakota planting zone map with the zone of each city shows how the zones are spread across the state and which plants are hardy in all of them.
Frequently Asked Questions
- When is the last frost in South Dakota?
- The average last spring frost in South Dakota falls between May 1 and May 14 for most ZIP codes, with a statewide median of May 6. Among major cities it ranges from April 26 in Sioux Falls to May 16 in Hot Springs.
- When is the last frost in Sioux Falls, South Dakota?
- Sioux Falls's average last spring frost is April 26, and by May 9 the chance of a later frost drops to 10%. Its first fall frost averages October 13, giving a 169-day growing season (NOAA station Sioux Falls WFO AP, SD).
- When should you plant tomatoes in South Dakota?
- Transplant tomatoes in South Dakota 1 to 2 weeks after the local average last frost, once nights stay above about 50 °F: May 3 – May 10 in Sioux Falls, May 10 – May 17 in Rapid City and May 15 – May 22 in Aberdeen. Start seeds indoors 6 to 8 weeks before the last frost.
- When is the first frost in South Dakota?
- The average first fall frost in South Dakota arrives between September 28 and October 9 for most ZIP codes, with a median of October 2. Harvest tender crops such as tomatoes, peppers and basil before then or cover them on cold nights.
- How long is the growing season in South Dakota?
- The frost-free growing season in South Dakota lasts about 136 to 161 days for most ZIP codes, with a median of 148 days, from 133 days in Hot Springs to 169 days in Sioux Falls.
Frost data: NOAA National Centers for Environmental Information, 1991–2020 U.S. Climate Normals (32 °F freeze dates by probability). ZIP code and city locations and populations: U.S. Census Bureau Gazetteer files and Vintage 2024 population estimates. Planting windows are general rules of thumb. PlantoScan is not affiliated with or endorsed by these agencies.