Frost dates / South Dakota / Rapid City
Frost dates in Rapid City, SD
The station on this page is RAPID CITY WFO, SD US (USC00396948), 0.4 miles from the city point. Population in the Census 2024 estimate is 79,894.
Zone 5bUSDA average annual extreme minimum -15°F to -10°F, from ZIP 57701 (3.6 miles from the city point used on this page).
Outside the median season Growing seasonTicks: 10%, 50%, and 90%
Last 32°F in spring
NCEI’s probability is the chance the last spring minimum of 32°F or lower occurs on or after the date.
| Probability | Date | How to read it |
|---|---|---|
| 90% | April 20 | Earlier date. A last 32°F on or after this day is common. |
| 50% | May 3 | Median. |
| 10% | May 17 | Later date. A last 32°F on or after this day is uncommon. |
First 32°F in fall
NCEI’s probability is the chance the first autumn minimum of 32°F or lower occurs on or before the date.
| Probability | Date | How to read it |
|---|---|---|
| 10% | September 26 | Earlier date. A first 32°F on or before this day is uncommon. |
| 50% | October 8 | Median. |
| 90% | October 23 | Later date. A first 32°F on or before this day is common. |
32°F growing-season length
Days between the last spring 32°F and the first autumn 32°F. The figure is a length the season meets or exceeds at that probability, from NCEI, not a subtraction done on this site.
| Probability the season is at least this long | Days |
|---|---|
| 10% | 176 |
| 50% | 157 |
| 90% | 137 |
28°F threshold
| 10% | 50% | 90% | |
|---|---|---|---|
| Last, on or after | May 5 | April 22 | April 8 |
| First, on or before | October 3 | October 18 | November 1 |
| Season at least | 200 days | 178 days | 157 days |
36°F threshold
| 10% | 50% | 90% | |
|---|---|---|---|
| Last, on or after | May 29 | May 15 | May 1 |
| First, on or before | September 19 | October 1 | October 14 |
| Season at least | 156 days | 137 days | 118 days |
Station RAPID CITY WFO, SD US (USC00396948). Completeness flag R, 23 years used for the 32°F dates. NCEI’s annual probability of at least one day at or below 32°F is 100%. Freeze dates are conditional on that threshold occurring. Elevation 1029.9 m. The same probability language applies to the 28°F and 36°F rows when those dates passed the same quality checks.
Check a crop against this station
Rapid City, SD
Zone 5bAverage annual extreme minimum -15°F to -10°F
Outside the median season Growing seasonTicks: 10%, 50%, and 90%
South Dakota. Nearest qualified station: RAPID CITY WFO, SD US (USC00396948), 0.4 miles. Median last 32°F May 3. Median first 32°F October 8. The 50% growing-season length is 157 days.
32°F probabilities at this station
| 10% | 50% | 90% | |
|---|---|---|---|
| Last 32°F on or after | May 17 | May 3 | April 20 |
| First 32°F on or before | September 26 | October 8 | October 23 |
Column order matches the NCEI file: for the last freeze, 10% is the later date and 90% is the earlier date. How to read the probabilities.
Planting calendar
Frost dates for South Dakota are above. Planting windows appear for states with a cited extension guide. The fall and seed tools use the numbers you enter and the station dates.
Date checks use your device’s calendar and appear after the page loads.