USDA Hardiness Zone 4b
Frost Dates for 57532 — Fort Pierre, South Dakota
NOAA 1991–2020 normals from Oahe Dam, SD (1,663 ft), 8 miles north.
Updated
In Fort Pierre, the last spring frost (32°F) is around May 6 in half of years and has passed by May 19 in nine years out of ten. The first fall frost comes around October 5, as early as September 23 one year in ten, leaving a typical freeze-free season of 152 days (NOAA, Oahe Dam, SD).
- Last spring frost
- May 6
- First fall frost
- October 5
- Growing season
- 152 days
- Hardiness zone
- 4b
50% probability
50% probability
freeze-free, 50%
-25 to -20°F (-31.7 to -28.9°C) coldest night
- First snow
- November 8
- Last snow
- April 13
- Winters with snow
- 100%
- Snow per year
- 37.2"
median, 1991–2020
median, 1991–2020
20 of 20 observed
NOAA normal
Frost risk by date in Fort Pierre
Half of springs at Oahe Dam, SD see their last 32°F night by May 6; only one in ten is past it by April 23, and one in ten still has one after May 19. Planting tender crops after May 11 leaves a 30% risk of a frost on them, after May 14 20%, and after May 19 10%. The 13 days between the even-odds date and the one-in-ten date is narrower than at 43% of the 49 South Dakota stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 5 in half of years, as early as September 23 one year in ten, and holds off past October 18 one year in ten. A hard freeze of 28°F follows 10 days later, around October 15; in spring the one-in-ten date for 28°F is May 10, 9 days before the 32°F one. The freeze-free season lasts 152 days in a typical year, longer than at 65% of the 49 South Dakota stations; it reaches 171 days one year in ten and falls short of 134 one year in ten. On average 169 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 9 days longer, to about May 15, and return around September 29. Severe cold of 16°F or below comes every winter, usually between November 8 and March 30.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 4 | May 8 | May 11 | May 13 | May 15 | May 17 | May 20 | May 23 | May 28 |
| 32°F | Apr 23 | Apr 28 | May 1 | May 3 | May 6 | May 8 | May 11 | May 14 | May 19 |
| 28°F | Apr 12 | Apr 16 | Apr 20 | Apr 24 | Apr 27 | Apr 30 | May 2 | May 5 | May 10 |
| 24°F | Apr 3 | Apr 7 | Apr 10 | Apr 13 | Apr 16 | Apr 18 | Apr 22 | Apr 26 | May 1 |
| 20°F | Mar 24 | Mar 30 | Apr 1 | Apr 4 | Apr 6 | Apr 8 | Apr 11 | Apr 16 | Apr 20 |
| 16°F | Mar 12 | Mar 19 | Mar 23 | Mar 27 | Mar 30 | Apr 1 | Apr 3 | Apr 7 | Apr 11 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 17 | Sep 21 | Sep 24 | Sep 27 | Sep 29 | Oct 1 | Oct 3 | Oct 5 | Oct 10 |
| 32°F | Sep 23 | Sep 28 | Oct 1 | Oct 3 | Oct 5 | Oct 8 | Oct 12 | Oct 15 | Oct 18 |
| 28°F | Oct 1 | Oct 4 | Oct 8 | Oct 12 | Oct 15 | Oct 17 | Oct 20 | Oct 23 | Oct 27 |
| 24°F | Oct 6 | Oct 14 | Oct 17 | Oct 20 | Oct 23 | Oct 26 | Oct 29 | Nov 1 | Nov 4 |
| 20°F | Oct 18 | Oct 23 | Oct 27 | Oct 30 | Nov 1 | Nov 4 | Nov 6 | Nov 10 | Nov 15 |
| 16°F | Oct 28 | Nov 1 | Nov 3 | Nov 6 | Nov 8 | Nov 11 | Nov 15 | Nov 19 | Nov 24 |
Freeze probabilities 1991–2020 at Oahe Dam, SD, from NOAA NCEI U.S. Climate Normals. Where a temperature is reached in fewer than 99.5% of years, the dates describe only the years that reach it. Not a forecast.
Frost risk on any date in 57532 →Compare Fort Pierre with another place →
Compared with the next station
The nearest other station, Pierre Regional Airport, SD, 8 miles northeast of Fort Pierre, has the same 50% last-frost date, a first frost 2 days earlier (October 3), a season 4 days shorter.
When it snows in Fort Pierre, South Dakota
The first measurable snow (0.1 inch or more) in Fort Pierre usually arrives around November 8, and the last of the season around April 13. Those are the middle dates across the winters of 1991–2020 at Pierre Regional Airport, SD, 8.3 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 23 days after the last snow.
Planting calendar for 57532
| When | What to do |
|---|---|
| February 25 – March 11 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 11 – March 25 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 8 – April 22 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 6 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 13 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 21 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 5 onward | Plant garlic, mulch beds, lift tender bulbsGarlic wants a cold spell; bare soil loses structure over winter. |
The weeks before and after the 50% dates are general rules of thumb, not NOAA figures; a seed packet gives the timing for each variety.
Where these figures come from
ZIP 57532 is 8 miles from Oahe Dam, SD, which stands at 1,663 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 57532 in zone 4b, the band where the coldest night of the year averaged -25 to -20°F (-31.7 to -28.9°C) over 1991–2020; a zone describes winter lows, not frost dates.
Frost dates across South Dakota →
Hardiness zone and temperature range: USDA Plant Hardiness Zone Map 2023 (USDA-ARS, Oregon State University), ZIP-code listing, unchanged. °C converted from °F by this site.
Thirty-year averages, not a forecast: check the forecast before planting out. How stations are matched and which pages are offered to search engines: methodology.