USDA Hardiness Zone 4b
Frost Dates for 57274 — Webster, South Dakota
NOAA 1991–2020 normals from Webster, SD (1,861 ft), 1 miles northeast.
Updated
In Webster, the last spring frost (32°F) is around May 4 in half of years and has passed by May 16 in nine years out of ten. The first fall frost comes around October 6, as early as September 25 one year in ten, leaving a typical freeze-free season of 156 days (NOAA, Webster, SD).
- Last spring frost
- May 4
- First fall frost
- October 6
- Growing season
- 156 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 9
- Last snow
- April 12
- Winters with snow
- 100%
- Snow per year
- 42.8"
median, 1991–2020
median, 1991–2020
30 of 30 observed
NOAA normal
Frost risk by date in Webster
Half of springs at Webster, SD see their last 32°F night by May 4; only one in ten is past it by April 20, and one in ten still has one after May 16. Planting tender crops after May 9 leaves a 30% risk of a frost on them, after May 12 20%, and after May 16 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 6 in half of years, as early as September 25 one year in ten, and holds off past October 20 one year in ten. A hard freeze of 28°F follows 10 days later, around October 16; in spring the one-in-ten date for 28°F is May 7, 9 days before the 32°F one. The freeze-free season lasts 156 days in a typical year, longer than at 71% of the 49 South Dakota stations; it reaches 172 days one year in ten and falls short of 137 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 9 days longer, to about May 13, and return around September 28. Severe cold of 16°F or below comes every winter, usually between November 9 and March 31.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 30 | May 5 | May 7 | May 10 | May 13 | May 15 | May 17 | May 20 | May 25 |
| 32°F | Apr 20 | Apr 26 | Apr 29 | May 1 | May 4 | May 6 | May 9 | May 12 | May 16 |
| 28°F | Apr 10 | Apr 15 | Apr 19 | Apr 22 | Apr 25 | Apr 28 | Apr 30 | May 3 | May 7 |
| 24°F | Apr 2 | Apr 6 | Apr 9 | Apr 12 | Apr 15 | Apr 18 | Apr 21 | Apr 25 | Apr 30 |
| 20°F | Mar 24 | Mar 31 | Apr 2 | Apr 4 | Apr 6 | Apr 9 | Apr 12 | Apr 16 | Apr 20 |
| 16°F | Mar 15 | Mar 20 | Mar 25 | Mar 29 | Mar 31 | Apr 2 | Apr 5 | Apr 8 | Apr 13 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 17 | Sep 20 | Sep 23 | Sep 26 | Sep 28 | Oct 1 | Oct 2 | Oct 6 | Oct 10 |
| 32°F | Sep 25 | Sep 29 | Oct 1 | Oct 4 | Oct 6 | Oct 9 | Oct 12 | Oct 15 | Oct 20 |
| 28°F | Oct 2 | Oct 6 | Oct 10 | Oct 13 | Oct 16 | Oct 18 | Oct 22 | Oct 24 | Oct 29 |
| 24°F | Oct 9 | Oct 15 | Oct 19 | Oct 22 | Oct 24 | Oct 27 | Oct 30 | Nov 2 | Nov 7 |
| 20°F | Oct 19 | Oct 24 | Oct 27 | Oct 31 | Nov 1 | Nov 4 | Nov 7 | Nov 11 | Nov 16 |
| 16°F | Oct 27 | Nov 1 | Nov 3 | Nov 6 | Nov 9 | Nov 11 | Nov 14 | Nov 18 | Nov 24 |
Freeze probabilities 1991–2020 at Webster, 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 57274 →Compare Webster with another place →
Weather by month in Webster
July is the warmest month at Webster, SD, averaging 81°F by day and 61°F at night; January is the coldest at 20°F and 2°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 64% of years.
Warmth for growing adds up to 2,392 growing degree days a year (base 50°F), fewer than at 82% of the 49 South Dakota stations. 32% of them (756) have built up by the end of June, and July adds the most, 651. Precipitation totals 26.2 inches a year, most in June (4.0") and least in November (0.7"); May to September bring 65% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 20 | 2 | 0.8 | 100% | 31 | 0 |
| Feb | 25 | 6 | 0.8 | 100% | 28 | 0 |
| Mar | 38 | 19 | 1.1 | 100% | 27 | 4 |
| Apr | 53 | 32 | 2.2 | 100% | 14 | 42 |
| May | 66 | 45 | 3.4 | 64% | 2 | 228 |
| Jun | 76 | 56 | 4.0 | 0% | 0 | 482 |
| Jul | 81 | 61 | 4.0 | 0% | 0 | 651 |
| Aug | 79 | 59 | 3.0 | 0% | 0 | 589 |
| Sep | 71 | 50 | 2.6 | 26% | <1 | 320 |
| Oct | 55 | 36 | 2.5 | 100% | 10 | 72 |
| Nov | 39 | 21 | 0.7 | 100% | 25 | 5 |
| Dec | 25 | 9 | 1.1 | 100% | 31 | 0 |
Monthly normals 1991–2020 at Webster, SD (1,861 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, Andover #2, SD, 19 miles west of Webster and 383 feet lower, has a last frost 2 days later (May 6), a first frost 2 days earlier (October 4), a season 6 days shorter.
When it snows in Webster, South Dakota
The first measurable snow (0.1 inch or more) in Webster usually arrives around November 9, and the last of the season around April 12. Those are the middle dates across the winters of 1991–2020 at Webster, SD, 1.4 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 57274
| When | What to do |
|---|---|
| February 23 – March 9 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 9 – March 23 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 6 – April 20 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| May 4 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 14 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 22 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 6 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 57274 is 1 mile from Webster, SD, which stands at 1,861 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 57274 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.