De Smet, South Dakota climate: Normal weather by month, frost dates and records
De Smet's normal year runs from 5°F January nights to 82°F July afternoons, with 25.9 inches of precipitation and 41 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 6.7°C, January lows of −15°C, July highs of 28°C, 659 mm of precipitation a year.
- NOAA stationDe Smet
- Station IDUSC00392302
- Location44.38°N 97.55°W
- Elevation1,705 ft (520 m)
- From the centerunder 1 mile
- Population1,037
On October 22, the normal high in De Smet is 54°F and the normal low 33°F, and the chance of measurable rain or snow is 17%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for De Smet.
- Jan 23° 5°
- Feb 29° 9°
- Mar 41° 21°
- Apr 55° 33°
- May 67° 45°
- Jun 77° 56°
- Jul 82° 61°
- Aug 79° 59°
- Sep 72° 50°
- Oct 57° 36°
- Nov 41° 22°
- Dec 28° 10°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in De Smet each month?
July is the warmest month, with normal highs of 82°F; January the coldest, with normal lows of 5°F. The most precipitation falls in June (4.06 in), the least in January (0.60 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 23°F | 5°F | 14.1°F | 0.60 | 6.2 | 4 | <1 | 31 | 9 h 10 min |
| February | 29°F | 9°F | 18.9°F | 0.88 | 9.2 | 4 | <1 | 27 | 10 h 30 min |
| March | 41°F | 21°F | 30.7°F | 1.36 | 6.9 | 5 | <1 | 26 | 11 h 50 min |
| April | 55°F | 33°F | 44.1°F | 2.30 | 4.8 | 7 | <1 | 13 | 13 h 20 min |
| May | 67°F | 45°F | 56.3°F | 3.32 | 0.0 | 10 | 1 | 2 | 14 h 50 min |
| June | 77°F | 56°F | 66.5°F | 4.06 | 0.0 | 10 | 1 | <1 | 15 h 30 min |
| July | 82°F | 61°F | 71.2°F | 3.88 | 0.0 | 8 | 5 | <1 | 15 h 10 min |
| August | 79°F | 59°F | 69.0°F | 3.07 | 0.0 | 7 | 2 | <1 | 14 h 10 min |
| September | 72°F | 50°F | 60.9°F | 2.78 | 0.0 | 6 | 1 | <1 | 12 h 40 min |
| October | 57°F | 36°F | 46.4°F | 1.98 | 1.6 | 6 | <1 | 10 | 11 h |
| November | 41°F | 22°F | 31.4°F | 0.96 | 5.4 | 4 | <1 | 24 | 9 h 40 min |
| December | 28°F | 10°F | 19.0°F | 0.74 | 7.3 | 4 | <1 | 31 | 8 h 50 min |
| Year (annual) | 54°F | 34°F | 44.0°F | 25.93 | 41.4 | 74 | 10 | 165 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −5°C | −15°C | −9.9°C | 15 mm | 16 cm |
| February | −2°C | −13°C | −7.3°C | 22 mm | 23 cm |
| March | 5°C | −6°C | −0.7°C | 35 mm | 18 cm |
| April | 13°C | 1°C | 6.7°C | 58 mm | 12 cm |
| May | 19°C | 7°C | 13.5°C | 84 mm | 0 cm |
| June | 25°C | 13°C | 19.2°C | 103 mm | 0 cm |
| July | 28°C | 16°C | 21.8°C | 99 mm | 0 cm |
| August | 26°C | 15°C | 20.6°C | 78 mm | 0 cm |
| September | 22°C | 10°C | 16.1°C | 71 mm | 0 cm |
| October | 14°C | 2°C | 8.0°C | 50 mm | 4 cm |
| November | 5°C | −6°C | −0.3°C | 24 mm | 14 cm |
| December | −2°C | −12°C | −7.2°C | 19 mm | 19 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00392302; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
When is the best weather to visit De Smet?
Normal highs sit between 65°F and 85°F in May, June, July, August and September. Of those, September has the fewest days with rain (6).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USC00392302.
When is the last frost in De Smet?
In De Smet, the last spring frost (32°F) comes after May 5 in half of years and after May 20 in one year in ten; the first autumn frost comes before October 4 in half of years and before September 23 in one year in ten.
Frost-free in half of yearsFrost in 1 to 9 years out of 10Frost most years
- Last spring frost, half of years after
- May 51 year in 10 after May 20; 9 in 10 after April 22
- First autumn frost, half of years before
- October 41 year in 10 before September 23; 9 in 10 before October 17
NOAA puts the median frost-free season at 151 days, and the season without a hard freeze (28°F) at 169 days.
A hard freeze (28°F) comes after April 28 in half of springs and before October 14 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts De Smet in zone 4b in ZIP code 57231, the nearest ZIP area. By the map's own method, the average of each year's coldest night over 1991-2020, De Smet's NOAA station is in zone 4b: the coldest night of a typical year reaches −21°F (26 complete years).
Frost dates for every NOAA station in South Dakota · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00392302; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; the station zone: ACIS daily lows, 1991-2020. A 10% date means one year in ten has a frost after it in spring or before it in autumn.
How hot and how cold does it get in De Smet?
In a normal year in De Smet, 10 days a year reach 90°F, 165 nights fall to 32°F or colder and 74 days bring measurable precipitation.
- Days at 90°F or more
- 10a normal year
- Days at 100°F or more
- fewer than 1a normal year
- Nights at 32°F or colder
- 165a normal year
- Days that stay below freezing
- 74high of 32°F or less
- Days with 0.01 inch of precipitation
- 74a normal year
- Days with 1 inch of snow or more
- 14a normal year
The highest temperature in this station's record (since 1893) is 111°F, on July 21, 1934; the lowest is −40°F, on February 10, 1899.
The wettest calendar year on that record is 2019, with 42.12 in; the snowiest season is 1987–88, with 80.5 inches.
Source: NOAA NCEI 1991-2020 annual normals, station USC00392302; records: ACIS (NOAA Regional Climate Centers), station USC00392302. Records use complete months only; a month missing more than three days is left out.
How sunny is De Smet?
Over a year 76% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around De Smet, 4.1 kWh per square metre a day. July is the sunniest month (85%) and December the cloudiest (67%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 77% | 2.0 |
| February | 79% | 3.0 |
| March | 71% | 3.8 |
| April | 71% | 4.9 |
| May | 72% | 5.7 |
| June | 77% | 6.4 |
| July | 85% | 6.7 |
| August | 82% | 5.6 |
| September | 79% | 4.4 |
| October | 73% | 2.9 |
| November | 73% | 2.0 |
| December | 67% | 1.4 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How much heating and cooling does De Smet need?
A normal year in De Smet brings 8,152 heating degree days, 52% more than the median U.S. place (5,373), and 547 cooling degree days, 40% fewer than the median (908). Seven months need 300 or more heating degree days, a monthly mean of about 55°F or colder. For gardens and crops, NOAA counts 2,461 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,579 | 0 |
| February | 1,292 | 0 |
| March | 1,062 | 0 |
| April | 628 | 1 |
| May | 294 | 23 |
| June | 62 | 107 |
| July | 15 | 209 |
| August | 28 | 152 |
| September | 176 | 52 |
| October | 580 | 3 |
| November | 1,010 | 0 |
| December | 1,426 | 0 |
| Year (annual) | 8,152 | 547 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00392302. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Has De Smet been warmer than normal lately?
2025 averaged 46.9°F, 2.9°F above the 1991-2020 normal of 44.0°F. 4 of the 5 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 47.2°F | +3.2°F | 25.41 | 33.8 |
| 2022 | 44.0°F | at normal | 18.28 | 23.3 |
| 2023 | 46.0°F | +2.0°F | 28.90 | 42.9 |
| 2024 | 47.4°F | +3.4°F | 29.37 | 32.4 |
| 2025 | 46.9°F | +2.9°F | 32.34 | 34.1 |
Over 77 complete years from 1898 to 2025, the station's annual mean temperature rose at a fitted 3.7°F per century (+0.21°C per decade). A fitted rate summarizes the whole record; single years swing well above and below it.
Source: observed years: ACIS, station USC00392302; trend: NOAA GHCN-Monthly v4. A year counts only with all twelve months complete.
How does De Smet's climate compare?
De Smet is warmer than 22 of the other 99 places with their own NOAA record in South Dakota, and wetter than 73. Across the 7,247 U.S. stations with normals, its annual mean of 44.0°F is warmer than 15%.
In the Köppen classification computed from these normals, De Smet is Dfb: continental, no dry season, warm summer. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Which places near De Smet share this climate record?
7 places have no NOAA station with 1991-2020 normals of their own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Lake Preston, SD605 people · 9 mi E
- Bryant, SD479 people · 15 mi N
- Iroquois, SD296 people · 15 mi W
- Willow Lake, SD268 people · 18 mi N
- Erwin, SD39 people · 9 mi NE
- Bancroft, SD13 people · 12 mi NW
- Collins Colony, SD0 people · 14 mi NW
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
Questions about De Smet's climate
What is the coldest month in De Smet?
January, with a normal high of 23°F and a normal low of 5°F. The warmest is July (82°F by day, 61°F at night).
Does it snow in De Smet?
Yes: 41 inches in a normal year, falling on 20 days with 0.1 inch or more, the most in February (9.2 inches).
What is the rainiest month in De Smet?
June, with 4.06 in of precipitation in a normal year; the driest is January with 0.60 in.
What plant hardiness zone is De Smet in?
The USDA's 2023 map puts De Smet in zone 4b in ZIP code 57231, the nearest ZIP area. By the same method at De Smet's NOAA station, the coldest night of a typical year reaches −21°F (26 years, 1991-2020): zone 4b.
How late can frost come in De Smet?
In half of years the last 32°F night comes after May 5; in one year in ten it comes after May 20. Waiting until May 20 leaves about a one-in-ten chance of a later frost.
Nearby and next
- South Dakota climateThe statewide normals and every place in the state
- Arlington, SD19 miles from this station, 44.7°F a year
- Howard, SD25 miles from this station, 46.6°F a year
- Winfred, SD30 miles from this station, 44.1°F a year
- Huron, SD34 miles from this station, 45.9°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made