Rapid City, South Dakota: planting zone & frost dates
Rapid City is in USDA plant hardiness zone 5a, where the average coldest winter night reaches -20 to -15°F (-28.9 to -26.1°C). The typical last spring frost is around May 9 and the first fall frost around Oct 1.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | May 17 | Sep 26 |
| Typical planning date (30% risk) | May 9 | Oct 1 |
| Median (50%) | May 3 | Oct 8 |
How to read this: after the spring "10% risk" date, a 32°F frost happens in only about 1 year in 10. In fall, the "10% risk" date is the early end — a frost before it happens about 1 year in 10.
Frost data comes from NOAA station RAPID CITY WFO, SD (USC00396948), 0.4 mi (0.6 km) from the city center and 13 ft lower than the city center (-4 m). Record used for the 1991–2020 normals: 23 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Rapid City
Rapid City spans more than one half-zone. Share of the city's land area by zone (via its 3 ZIP codes): 5a (58%), 5b (42%). The headline zone is the one covering the most land. Look up your ZIP for your exact zone.
Vegetable planting calendar for Rapid City
Dates are counted from the 30%-risk frost dates above (last frost May 9, first frost Oct 1). Shift a week later in cold spots or low-lying ground.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Mar 14 – Mar 28 | May 16 – May 30 | — | — |
| Pepper | Feb 28 – Mar 14 | May 23 – Jun 6 | — | — |
| Lettuce | Mar 28 – Apr 11 | Apr 25 – May 16 | Apr 11 – May 23 | Jul 23 – Aug 20 |
| Green Beans | — | — | May 16 – Jun 20 | Jul 9 – Jul 23 |
| Sweet Corn | — | — | May 16 – Jun 13 | — |
| Zucchini & Summer Squash | Apr 11 – Apr 18 | May 16 – May 30 | May 16 – Jun 6 | Jul 9 – Jul 23 |
| Cucumber | Apr 11 – Apr 18 | May 23 – May 30 | May 16 – Jun 6 | Jul 9 – Jul 23 |
| Carrot | — | — | Apr 18 – May 23 | Jul 9 – Jul 23 |
| Onion | Feb 14 – Feb 28 | Apr 11 – Apr 25 | — | — |
| Potato | — | Apr 11 – May 2 | — | — |
| Basil | Mar 28 – Apr 11 | May 23 – Jun 6 | May 23 – Jun 13 | — |
| Spinach | — | — | Mar 28 – Apr 25 | Aug 6 – Sep 3 |
| Kale | Mar 14 – Mar 28 | Apr 11 – May 2 | Apr 11 – May 2 | Jul 23 – Aug 20 |
| Broccoli | Mar 14 – Mar 28 | Apr 25 – May 16 | — | Jul 9 – Jul 23 |
| Peas | — | — | Mar 28 – Apr 18 | Jul 23 – Aug 6 |
| Eggplant | Feb 28 – Mar 14 | May 23 – Jun 6 | — | — |
| Cabbage | Mar 14 – Mar 28 | Apr 11 – Apr 25 | — | Jul 9 – Jul 23 |
| Radish | — | — | Apr 4 – May 23 | Aug 20 – Sep 17 |
| Strawberry | — | Apr 11 – May 2 | — | — |
| Beets | — | — | Apr 18 – May 30 | Jul 23 – Aug 6 |
Nearby cities in South Dakota
- Sioux Falls — zone 5a, last frost May 6, first frost Sep 30
More: all South Dakota cities · other zone 5a cities: Minneapolis, MN, St. Paul, MN, Anchorage, AK, Sioux Falls, SD, Cedar Rapids, IA, Billings, MT, Bloomington, MN, Sioux City, IA
Rapid City gardening questions
When is the last frost in Rapid City, SD?
Plan around May 9. At NOAA's Rapid City Wfo, SD station, 0.4 mi from the city center, there is a 30% chance of a 32°F frost after that date. Half of springs have their last frost by May 3, and after May 17 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Apr 22. The last frost is fairly predictable here: only 27 days separate the 90% and 10% dates (median for cities on this site: 36 days).
When should I plant tomatoes in Rapid City, SD?
Start seeds indoors Mar 14 – Mar 28 and set transplants outside May 16 – May 30, once nights stay above 50°F and the soil is near 60°F. That leaves 145 days between the 30% frost dates, enough for most varieties including 80–85-day slicers. More: tomato planting dates by zone.
How long is the growing season in Rapid City?
About 157 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 137 days, and in 1 year in 10 it runs 176 days or more. In fall there is a 10% chance of frost by Sep 26 and a 30% chance by Oct 1.
When should I plant a fall garden in Rapid City?
Count back from the first fall frost (Oct 1): transplant broccoli Jul 9 – Jul 23; sow kale Jul 23 – Aug 20; sow lettuce Jul 23 – Aug 20; sow radishes Aug 20 – Sep 17. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Oct 18. How the math works: succession and fall planting.
Did Rapid City's hardiness zone change on the 2023 map?
No. Going by the zone that covers most of the city's land, Rapid City is zone 5a on both the 2012 and the 2023 USDA maps (PRISM/OSU ZIP listings). About 42% of U.S. ZIP codes kept their half-zone in 2023. Why the 2023 map is warmer.
Is all of Rapid City in zone 5a?
No. Zone 5a covers about 58% of the city's land; the rest is in 5b (42%), measured across the city's 3 ZIP codes. Check your own ZIP code in the table above or with the ZIP lookup.