USDA Hardiness Zone 4b
Frost Dates for 57006 — Brookings, South Dakota
NOAA 1991–2020 normals from Brookings 2 NE, SD (1,639 ft), 2 miles northeast.
Updated
In Brookings, 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 1, as early as September 17 one year in ten, leaving a typical freeze-free season of 145 days (NOAA, Brookings 2 NE, SD).
- Last spring frost
- May 6
- First fall frost
- October 1
- Growing season
- 145 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 7
- Last snow
- April 14
- Winters with snow
- 100%
- Snow per year
- 35.8"
median, 1991–2020
median, 1991–2020
28 of 28 observed
NOAA normal
Frost risk by date in Brookings
Half of springs at Brookings 2 NE, SD see their last 32°F night by May 6; only one in ten is past it by April 25, 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 1 in half of years, as early as September 17 one year in ten, and holds off past October 13 one year in ten. A hard freeze of 28°F follows 7 days later, around October 8; 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 145 days in a typical year, shorter than at 67% of the 49 South Dakota stations; it reaches 163 days one year in ten and falls short of 127 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 15, and return around September 22. Severe cold of 16°F or below comes every winter, usually between November 6 and March 31.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 3 | May 7 | May 10 | May 13 | May 15 | May 18 | May 21 | May 25 | May 29 |
| 32°F | Apr 25 | Apr 29 | May 2 | May 4 | May 6 | May 9 | May 11 | May 14 | May 19 |
| 28°F | Apr 13 | Apr 18 | Apr 21 | Apr 24 | Apr 28 | Apr 30 | May 2 | May 5 | May 10 |
| 24°F | Apr 3 | Apr 8 | Apr 12 | Apr 14 | Apr 17 | Apr 20 | Apr 24 | Apr 28 | May 2 |
| 20°F | Mar 22 | Mar 30 | Apr 2 | Apr 5 | Apr 8 | Apr 10 | Apr 14 | Apr 18 | Apr 23 |
| 16°F | Mar 13 | Mar 18 | Mar 23 | Mar 27 | Mar 31 | Apr 2 | Apr 6 | Apr 9 | Apr 14 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 6 | Sep 12 | Sep 16 | Sep 19 | Sep 22 | Sep 25 | Sep 28 | Oct 1 | Oct 5 |
| 32°F | Sep 17 | Sep 22 | Sep 25 | Sep 29 | Oct 1 | Oct 3 | Oct 5 | Oct 9 | Oct 13 |
| 28°F | Sep 25 | Sep 30 | Oct 2 | Oct 5 | Oct 8 | Oct 12 | Oct 15 | Oct 19 | Oct 24 |
| 24°F | Oct 3 | Oct 8 | Oct 13 | Oct 17 | Oct 20 | Oct 23 | Oct 26 | Oct 29 | Nov 2 |
| 20°F | Oct 18 | Oct 22 | Oct 26 | Oct 28 | Oct 31 | Nov 1 | Nov 4 | Nov 7 | Nov 12 |
| 16°F | Oct 26 | Oct 30 | Nov 2 | Nov 4 | Nov 6 | Nov 9 | Nov 13 | Nov 15 | Nov 20 |
Freeze probabilities 1991–2020 at Brookings 2 NE, 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 57006 →Compare Brookings with another place →
Weather by month in Brookings
July is the warmest month at Brookings 2 NE, SD, averaging 81°F by day and 60°F at night; January is the coldest at 22°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 74% of years.
Warmth for growing adds up to 2,395 growing degree days a year (base 50°F), fewer than at 80% of the 49 South Dakota stations. 33% of them (783) have built up by the end of June, and July adds the most, 643. Precipitation totals 25.3 inches a year, most in June (4.3") and least in January (0.4"); May to September bring 70% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 22 | 4 | 0.4 | 100% | 31 | 0 |
| Feb | 27 | 7 | 0.5 | 100% | 28 | 0 |
| Mar | 39 | 20 | 1.1 | 100% | 27 | 6 |
| Apr | 54 | 32 | 2.2 | 100% | 16 | 47 |
| May | 67 | 45 | 3.5 | 74% | 2 | 233 |
| Jun | 77 | 56 | 4.3 | 0% | 0 | 497 |
| Jul | 81 | 60 | 3.6 | 0% | 0 | 643 |
| Aug | 79 | 57 | 3.2 | 0% | 0 | 569 |
| Sep | 72 | 48 | 3.1 | 47% | 2 | 321 |
| Oct | 58 | 34 | 2.0 | 100% | 14 | 73 |
| Nov | 41 | 22 | 0.8 | 100% | 26 | 6 |
| Dec | 28 | 10 | 0.6 | 100% | 31 | 0 |
Monthly normals 1991–2020 at Brookings 2 NE, SD (1,639 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, Flandreau, SD, 20 miles southeast of Brookings, has a last frost 1 day earlier (May 5), the same first-frost date, a season 3 days longer.
When it snows in Brookings, South Dakota
The first measurable snow (0.1 inch or more) in Brookings usually arrives around November 7, and the last of the season around April 14. Those are the middle dates across the winters of 1991–2020 at Brookings 2 NE, SD, 1.7 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 57006
| 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 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 57006 is 2 miles from Brookings 2 NE, SD, which stands at 1,639 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 57006 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.