USDA Hardiness Zone 4b
Frost Dates for 57350 — Huron, South Dakota
NOAA 1991–2020 normals from Huron Regional Airport, SD (1,280 ft), 2 miles northwest.
Updated
In Huron, the last spring frost (32°F) is around May 6 in half of years and has passed by May 20 in nine years out of ten. The first fall frost comes around October 2, as early as September 19 one year in ten, leaving a typical freeze-free season of 146 days (NOAA, Huron Regional Airport, SD).
- Last spring frost
- May 6
- First fall frost
- October 2
- Growing season
- 146 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 14
- Winters with snow
- 100%
- Snow per year
- 44.4"
median, 1991–2020
median, 1991–2020
30 of 30 observed
NOAA normal
Frost risk by date in Huron
Half of springs at Huron Regional Airport, 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 20. Planting tender crops after May 12 leaves a 30% risk of a frost on them, after May 15 20%, and after May 20 10%. The 14 days between the even-odds date and the one-in-ten date is wider than at 59% of the 49 South Dakota stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 2 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 6 days later, around October 8; in spring the one-in-ten date for 28°F is May 11, 9 days before the 32°F one. The freeze-free season lasts 146 days in a typical year, shorter than at 63% of the 49 South Dakota stations; it reaches 165 days one year in ten and falls short of 128 one year in ten. On average 167 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 10 days longer, to about May 16, and return around September 24. Severe cold of 16°F or below comes every winter, usually between November 5 and March 29.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | May 3 | May 7 | May 10 | May 14 | May 16 | May 19 | May 21 | May 24 | May 28 |
| 32°F | Apr 23 | Apr 28 | May 1 | May 4 | May 6 | May 9 | May 12 | May 15 | May 20 |
| 28°F | Apr 12 | Apr 17 | Apr 20 | Apr 24 | Apr 27 | Apr 30 | May 2 | May 5 | May 11 |
| 24°F | Apr 4 | Apr 7 | Apr 11 | Apr 13 | Apr 16 | Apr 20 | Apr 23 | Apr 27 | May 2 |
| 20°F | Mar 23 | Mar 30 | Apr 2 | Apr 4 | Apr 7 | Apr 10 | Apr 13 | Apr 17 | Apr 23 |
| 16°F | Mar 12 | Mar 17 | Mar 22 | Mar 26 | Mar 29 | Apr 1 | Apr 4 | Apr 8 | Apr 15 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 10 | Sep 15 | Sep 19 | Sep 22 | Sep 24 | Sep 27 | Sep 29 | Oct 2 | Oct 5 |
| 32°F | Sep 19 | Sep 23 | Sep 27 | Sep 30 | Oct 2 | Oct 4 | Oct 7 | Oct 10 | Oct 14 |
| 28°F | Sep 26 | Sep 30 | Oct 2 | Oct 5 | Oct 8 | Oct 11 | Oct 14 | Oct 18 | Oct 22 |
| 24°F | Oct 4 | Oct 8 | Oct 12 | Oct 16 | Oct 19 | Oct 22 | Oct 24 | Oct 28 | Nov 1 |
| 20°F | Oct 12 | Oct 18 | Oct 22 | Oct 26 | Oct 28 | Oct 31 | Nov 3 | Nov 6 | Nov 12 |
| 16°F | Oct 22 | Oct 28 | Nov 1 | Nov 3 | Nov 5 | Nov 9 | Nov 12 | Nov 16 | Nov 20 |
Freeze probabilities 1991–2020 at Huron Regional Airport, 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 57350 →Compare Huron with another place →
Weather by month in Huron
July is the warmest month at Huron Regional Airport, SD, averaging 86°F by day and 62°F at night; January is the coldest at 26°F and 6°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 2,793 growing degree days a year (base 50°F), more than at 61% of the 49 South Dakota stations. 32% of them (907) have built up by the end of June, and July adds the most, 733. Precipitation totals 23.5 inches a year, most in June (3.9") and least in January (0.6"); May to September bring 63% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 26 | 6 | 0.6 | 100% | 31 | 0 |
| Feb | 31 | 10 | 0.8 | 100% | 27 | 1 |
| Mar | 44 | 22 | 1.2 | 100% | 26 | 13 |
| Apr | 58 | 34 | 2.5 | 100% | 13 | 67 |
| May | 70 | 46 | 3.2 | 71% | 2 | 276 |
| Jun | 80 | 57 | 3.9 | 0% | 0 | 551 |
| Jul | 86 | 62 | 2.8 | 0% | 0 | 733 |
| Aug | 83 | 59 | 2.6 | 0% | 0 | 660 |
| Sep | 76 | 50 | 2.4 | 44% | 1 | 388 |
| Oct | 60 | 36 | 2.0 | 100% | 11 | 97 |
| Nov | 44 | 22 | 0.8 | 100% | 25 | 9 |
| Dec | 30 | 11 | 0.7 | 100% | 31 | 0 |
Monthly normals 1991–2020 at Huron Regional Airport, SD (1,280 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, Redfield, SD, 37 miles northwest of Huron, has a last frost 2 days later (May 8), a first frost 1 day earlier (October 1), a season 1 day shorter.
When it snows in Huron, South Dakota
The first measurable snow (0.1 inch or more) in Huron usually arrives around November 5, and the last of the season around April 14. Those are the middle dates across the winters of 1991–2020 at Huron Regional Airport, SD, 1.6 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 57350
| 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 10 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 18 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 2 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 57350 is 2 miles from Huron Regional Airport, SD, which stands at 1,280 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 57350 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.