Rapid City, South Dakota frost dates
Frost risk by date
| Chance of frost | Spring: frost after | Fall: frost before |
|---|---|---|
| 90% | May 1 | October 14 |
| 70% | May 7 | October 5 |
| 50% | May 12 | October 1 |
| 30% | May 18 | September 25 |
| 10% | May 26 | September 16 |
Read the spring column like this: there is a 10% chance of a 32°F freeze after May 26. These are NOAA probabilities for the Rapid City Regional Airport weather station (USW00024090, elevation 963 m), 1991–2020.
Rapid City vegetable planting calendar
Dates count from the 50% last-frost date (May 12). For tomatoes, peppers and other frost-tender crops, waiting until the 10% date (May 26) is the cautious choice.
| Crop | Start seeds indoors | Plant out |
|---|---|---|
| Beans | Apr 21 | May 19 (usually sown directly in the garden) |
| Broccoli | Mar 3 | Apr 14 |
| Brussels sprouts | Mar 3 | Apr 14 |
| Cabbage | Feb 24 | Apr 7 |
| Cauliflower | Mar 17 | Apr 28 |
| Sweet corn | Apr 14 | May 12 (usually sown directly in the garden) |
| Cucumbers | Apr 28 | May 19 |
| Kale | Feb 24 | Apr 7 |
| Leeks | Jan 27 | Apr 7 |
| Lettuce | Mar 24 | Apr 28 |
| Melons | May 5 | May 26 |
| Onions | Jan 20 | Mar 31 (from seed; sets and transplants go out at the same time) |
| Peas | Mar 17 | Apr 14 (usually sown directly in the garden) |
| Peppers | Mar 31 | May 26 |
| Squash | May 5 | May 26 |
| Tomatoes | Mar 17 | May 12 |
Offsets from Oregon State University Extension's seed-starting table. "Plant out" means transplant, or sow directly for crops usually grown from seed.
Fall frost and season extension
The first fall freeze usually arrives around October 1. There's a 1-in-10 chance it comes before September 16. Harvest tender crops such as basil, tomatoes, peppers and squash before then, or cover them on cold nights. Cool-season crops like kale, cabbage and Brussels sprouts handle light frost, and often taste sweeter after it. A hard freeze (28°F) typically comes around October 9.
Nearby cities
| City | Last frost (50%) | First frost (50%) | Distance |
|---|---|---|---|
| Cheyenne, WY | May 12 | Oct 1 | ~350 km |
| Bismarck, ND | May 14 | Sep 27 | ~354 km |
| Billings, MT | May 4 | Oct 7 | ~480 km |
| Denver, CO | May 5 | Oct 9 | ~485 km |
| Sioux Falls, SD | May 1 | Oct 6 | ~507 km |
| Fargo, ND | May 10 | Sep 30 | ~592 km |