USDA Hardiness Zone 4b
Frost Dates for 57028 — Flandreau, South Dakota
NOAA 1991–2020 normals from Flandreau, SD (1,567 ft), under a mile northwest.
Updated
In Flandreau, the last spring frost (32°F) is around May 5 in half of years and has passed by May 17 in nine years out of ten. The first fall frost comes around October 1, as early as September 19 one year in ten, leaving a typical freeze-free season of 148 days (NOAA, Flandreau, SD).
- Last spring frost
- May 5
- First fall frost
- October 1
- Growing season
- 148 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 5
- Last snow
- April 13
- Winters with snow
- 100%
- Snow per year
- 40.4"
median, 1991–2020
median, 1991–2020
27 of 27 observed
NOAA normal
Frost risk by date in Flandreau
Half of springs at Flandreau, SD see their last 32°F night by May 5; only one in ten is past it by April 23, and one in ten still has one after May 17. Planting tender crops after May 9 leaves a 30% risk of a frost on them, after May 13 20%, and after May 17 10%. The 12 days between the even-odds date and the one-in-ten date is narrower than at 90% of the 49 South Dakota stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 1 in half of years, as early as September 19 one year in ten, and holds off past October 14 one year in ten. A hard freeze of 28°F follows 10 days later, around October 11; in spring the one-in-ten date for 28°F is May 8, 9 days before the 32°F one. The freeze-free season lasts 148 days in a typical year, shorter than at 51% of the 49 South Dakota stations; it reaches 166 days one year in ten and falls short of 130 one year in ten. On average 177 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 14, and return around September 24. Severe cold of 16°F or below comes every winter, usually between November 7 and March 31.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 3 | May 7 | May 9 | May 11 | May 14 | May 16 | May 18 | May 21 | May 26 |
| 32°F | Apr 23 | Apr 28 | May 1 | May 3 | May 5 | May 7 | May 9 | May 13 | May 17 |
| 28°F | Apr 12 | Apr 16 | Apr 20 | Apr 23 | Apr 26 | Apr 28 | Apr 30 | May 4 | May 8 |
| 24°F | Apr 2 | Apr 7 | Apr 10 | Apr 13 | Apr 16 | Apr 19 | Apr 21 | Apr 25 | Apr 30 |
| 20°F | Mar 23 | Mar 31 | Apr 3 | Apr 5 | Apr 8 | Apr 11 | Apr 14 | Apr 18 | Apr 22 |
| 16°F | Mar 14 | Mar 20 | Mar 24 | Mar 29 | Mar 31 | Apr 3 | Apr 6 | Apr 10 | Apr 16 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 9 | Sep 14 | Sep 18 | Sep 20 | Sep 24 | Sep 26 | Sep 29 | Oct 1 | Oct 6 |
| 32°F | Sep 19 | Sep 24 | Sep 27 | Sep 29 | Oct 1 | Oct 4 | Oct 7 | Oct 10 | Oct 14 |
| 28°F | Sep 27 | Oct 1 | Oct 5 | Oct 7 | Oct 11 | Oct 14 | Oct 17 | Oct 19 | Oct 24 |
| 24°F | Oct 8 | Oct 13 | Oct 17 | Oct 20 | Oct 22 | Oct 24 | Oct 27 | Oct 31 | Nov 3 |
| 20°F | Oct 19 | Oct 23 | Oct 26 | Oct 29 | Oct 31 | Nov 2 | Nov 4 | Nov 8 | Nov 12 |
| 16°F | Oct 26 | Oct 30 | Nov 1 | Nov 4 | Nov 7 | Nov 9 | Nov 12 | Nov 16 | Nov 22 |
Freeze probabilities 1991–2020 at Flandreau, 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 57028 →Compare Flandreau with another place →
Weather by month in Flandreau
July is the warmest month at Flandreau, SD, averaging 81°F by day and 60°F at night; January is the coldest at 23°F and 4°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 71% of years.
Warmth for growing adds up to 2,376 growing degree days a year (base 50°F), fewer than at 84% of the 49 South Dakota stations. 33% of them (776) have built up by the end of June, and July adds the most, 638. Precipitation totals 28.5 inches a year, most in June (4.5") and least in January (0.5"); May to September bring 67% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 23 | 4 | 0.5 | 100% | 31 | 0 |
| Feb | 28 | 7 | 0.8 | 100% | 28 | 0 |
| Mar | 40 | 19 | 1.3 | 100% | 27 | 6 |
| Apr | 54 | 31 | 2.7 | 100% | 16 | 46 |
| May | 67 | 45 | 4.1 | 71% | 2 | 229 |
| Jun | 77 | 56 | 4.5 | 0% | 0 | 494 |
| Jul | 81 | 60 | 3.8 | 0% | 0 | 638 |
| Aug | 79 | 57 | 3.6 | 0% | 0 | 561 |
| Sep | 72 | 48 | 3.1 | 45% | 1 | 319 |
| Oct | 58 | 34 | 2.2 | 100% | 14 | 76 |
| Nov | 41 | 21 | 1.0 | 100% | 26 | 6 |
| Dec | 28 | 10 | 0.9 | 100% | 31 | 0 |
Monthly normals 1991–2020 at Flandreau, SD (1,567 ft), NOAA NCEI. "32°F night": chance of at least one in the month. GDD: growing degree days, base 50°F.
Compared with the next station
The nearest other station, Pipestone, MN, 13 miles east of Flandreau, has a last frost 1 day earlier (May 4), a first frost 1 day later (October 2), a season 4 days longer.
When it snows in Flandreau, South Dakota
The first measurable snow (0.1 inch or more) in Flandreau usually arrives around November 5, and the last of the season around April 13. Those are the middle dates across the winters of 1991–2020 at Flandreau, SD, 0.3 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 22 days after the last snow.
Planting calendar for 57028
| When | What to do |
|---|---|
| February 24 – March 10 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 10 – March 24 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 7 – April 21 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 5 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 9 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 17 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 1 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 57028 is under a mile from Flandreau, SD, which stands at 1,567 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 57028 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.