Gann Valley, South Dakota climate: Normal weather by month, frost dates and records
Gann Valley's normal year runs from 4°F January nights to 87°F July afternoons, with 22.7 inches of precipitation and 41 inches of snow a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 7.3°C, January lows of −16°C, July highs of 31°C, 576 mm of precipitation a year.
- NOAA stationGann Valley (3 mi NNE)
- Station IDUSC00393211
- Location44.08°N 98.97°W
- Elevation1,646 ft (502 m)
- Population (census place)5
On October 23, the normal high in Gann Valley is 57°F and the normal low 29°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 Gann Valley.
- Jan 27° 4°
- Feb 31° 9°
- Mar 45° 19°
- Apr 58° 31°
- May 70° 44°
- Jun 80° 56°
- Jul 87° 61°
- Aug 85° 58°
- Sep 77° 48°
- Oct 61° 32°
- Nov 45° 20°
- Dec 31° 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 Gann Valley each month?
July is the warmest month, with normal highs of 87°F; January the coldest, with normal lows of 4°F. The most precipitation falls in June (4.22 in), the least in January (0.32 in).
| Month | High | Low | Mean | Precip. | Snow | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | 27°F | 4°F | 15.1°F | 0.32 | 7.8 | 5 | <1 | 31 | 9 h 10 min |
| February | 31°F | 9°F | 19.9°F | 0.61 | 9.3 | 5 | <1 | 28 | 10 h 30 min |
| March | 45°F | 19°F | 31.8°F | 0.98 | 4.6 | 6 | <1 | 27 | 11 h 50 min |
| April | 58°F | 31°F | 44.3°F | 1.69 | 5.4 | 9 | <1 | 16 | 13 h 20 min |
| May | 70°F | 44°F | 56.9°F | 3.35 | 0.0 | 11 | 1 | 3 | 14 h 40 min |
| June | 80°F | 56°F | 67.6°F | 4.22 | 0.0 | 11 | 5 | <1 | 15 h 30 min |
| July | 87°F | 61°F | 74.0°F | 3.20 | 0.0 | 9 | 12 | <1 | 15 h 10 min |
| August | 85°F | 58°F | 71.5°F | 2.91 | 0.0 | 9 | 7 | <1 | 14 h |
| September | 77°F | 48°F | 62.4°F | 2.82 | 0.0 | 6 | 3 | 1 | 12 h 40 min |
| October | 61°F | 32°F | 46.6°F | 1.55 | 1.8 | 6 | <1 | 15 | 11 h 10 min |
| November | 45°F | 20°F | 32.3°F | 0.71 | 2.4 | 3 | <1 | 27 | 9 h 40 min |
| December | 31°F | 10°F | 20.1°F | 0.32 | 9.6 | 6 | <1 | 31 | 8 h 50 min |
| Year (annual) | 58°F | 33°F | 45.2°F | 22.68 | 40.9 | 86 | 28 | 179 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. | Snow |
|---|---|---|---|---|---|
| January | −3°C | −16°C | −9.4°C | 8 mm | 20 cm |
| February | 0°C | −13°C | −6.7°C | 15 mm | 24 cm |
| March | 7°C | −7°C | −0.1°C | 25 mm | 12 cm |
| April | 14°C | 0°C | 6.8°C | 43 mm | 14 cm |
| May | 21°C | 7°C | 13.8°C | 85 mm | 0 cm |
| June | 26°C | 13°C | 19.8°C | 107 mm | 0 cm |
| July | 31°C | 16°C | 23.3°C | 81 mm | 0 cm |
| August | 29°C | 15°C | 21.9°C | 74 mm | 0 cm |
| September | 25°C | 9°C | 16.9°C | 72 mm | 0 cm |
| October | 16°C | 0°C | 8.1°C | 39 mm | 5 cm |
| November | 7°C | −7°C | 0.2°C | 18 mm | 6 cm |
| December | −1°C | −12°C | −6.6°C | 8 mm | 24 cm |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00393211; 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 Gann Valley?
Normal highs sit between 65°F and 85°F in May, June, 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 USC00393211.
When is the last frost in Gann Valley?
In Gann Valley, the last spring frost (32°F) comes after May 7 in half of years and after May 21 in one year in ten; the first autumn frost comes before October 1 in half of years and before September 19 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 71 year in 10 after May 21; 9 in 10 after April 25
- First autumn frost, half of years before
- October 11 year in 10 before September 19; 9 in 10 before October 13
NOAA puts the median frost-free season at 146 days, and the season without a hard freeze (28°F) at 162 days.
A hard freeze (28°F) comes after April 30 in half of springs and before October 8 in half of autumns.
The USDA's 2023 Plant Hardiness Zone Map puts Gann Valley in zone 4b in ZIP code 57341, the nearest ZIP area.
Frost dates for every NOAA station in South Dakota · Frost dates by ZIP code
Source: NOAA NCEI 1991-2020 annual normals (frost probabilities), station USC00393211; USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026. 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 Gann Valley?
In a normal year in Gann Valley, 28 days a year reach 90°F (3 of them 100°F or more), 179 nights fall to 32°F or colder and 86 days bring measurable precipitation.
- Days at 90°F or more
- 28a normal year
- Days at 100°F or more
- 3a normal year
- Nights at 32°F or colder
- 179a normal year
- Days that stay below freezing
- 71high of 32°F or less
- Days with 0.01 inch of precipitation
- 86a normal year
- Days with 1 inch of snow or more
- 14a normal year
Source: NOAA NCEI 1991-2020 annual normals, station USC00393211.
How sunny is Gann Valley?
Over a year 77% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Gann Valley, 4.1 kWh per square metre a day. July is the sunniest month (86%) and December the cloudiest (70%).
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 78% | 2.0 |
| February | 80% | 3.0 |
| March | 73% | 3.9 |
| April | 72% | 5.0 |
| May | 73% | 5.8 |
| June | 79% | 6.5 |
| July | 86% | 6.8 |
| August | 83% | 5.7 |
| September | 80% | 4.4 |
| October | 74% | 3.0 |
| November | 74% | 2.0 |
| December | 70% | 1.5 |
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 Gann Valley need?
A normal year in Gann Valley brings 7,912 heating degree days, 47% more than the median U.S. place (5,373), and 745 cooling degree days, 18% 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 2,752 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 1,545 | 0 |
| February | 1,262 | 0 |
| March | 1,029 | 1 |
| April | 622 | 1 |
| May | 280 | 30 |
| June | 54 | 131 |
| July | 5 | 283 |
| August | 20 | 221 |
| September | 151 | 72 |
| October | 574 | 6 |
| November | 980 | 0 |
| December | 1,391 | 0 |
| Year (annual) | 7,912 | 745 |
Source: NOAA NCEI 1991-2020 monthly normals, station USC00393211. 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 Gann Valley been warmer than normal lately?
2024 averaged 46.1°F, 0.9°F above the 1991-2020 normal of 45.2°F. 2 of the 3 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. | Snow |
|---|---|---|---|---|
| 2021 | 46.7°F | +1.5°F | 18.29 | 25.8 |
| 2022 | 43.6°F | −1.6°F | 16.63 | 31.2 |
| 2024 | 46.1°F | +0.9°F | 20.55 | 29.7 |
Source: observed years: ACIS, station USC00393211. A year counts only with all twelve months complete.
How does Gann Valley's climate compare?
Gann Valley is warmer than 40 of the other 99 places with their own NOAA record in South Dakota, and wetter than 49. Across the 7,247 U.S. stations with normals, its annual mean of 45.2°F is warmer than 20%.
In the Köppen classification computed from these normals, Gann Valley is Dwa: continental, dry-winter, hot 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 Gann Valley share this climate record?
Spring Valley Colony has no NOAA station with 1991-2020 normals of its 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.
- Spring Valley Colony, SD0 people · 5 mi SE
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
What do Gann Valley's other NOAA stations record?
One more NOAA station keeps 1991-2020 normals in or near Gann Valley. This page uses Gann Valley (3 mi NNE); the other differs by site and elevation:
| Station | From this station | Elevation | Year | Jan low | Jul high | Precip. | Snow | Last frost |
|---|---|---|---|---|---|---|---|---|
| Gann Valley (4 mi NW) USC00393217 | 5 mi W | 1,720 ft | 45.8°F | 6°F | 87°F | – | – | May 6 |
Source: NOAA NCEI 1991-2020 normals for each station. Last frost: the median last spring date of 32°F.
Questions about Gann Valley's climate
What is the coldest month in Gann Valley?
January, with a normal high of 27°F and a normal low of 4°F. The warmest is July (87°F by day, 61°F at night).
Does it snow in Gann Valley?
Yes: 41 inches in a normal year, falling on 24 days with 0.1 inch or more, the most in December (9.6 inches).
What is the rainiest month in Gann Valley?
June, with 4.22 in of precipitation in a normal year; the driest is January with 0.32 in.
What plant hardiness zone is Gann Valley in?
The USDA's 2023 map puts Gann Valley in zone 4b in ZIP code 57341, the nearest ZIP area.
How late can frost come in Gann Valley?
In half of years the last 32°F night comes after May 7; in one year in ten it comes after May 21. Waiting until May 21 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
- Wessington Springs, SD20 miles from this station, 45.4°F a year
- Lake Sharpe Project, SD24 miles from this station, 46.7°F a year
- Stephan, SD27 miles from this station, 44.6°F a year
- Chamberlain, SD27 miles from this station, 48.2°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made