Gann Valley weather by month
What a typical year looks like in Gann Valley, South Dakota: average highs and lows, rain and snow, and the warmest and coldest days on record. Normals are the 1991–2020 averages at Gann Valley 3 Nne, 5 km from Gann Valley; records cover 2009–2026.
The year at a glance
- Precipitation a year
- 22.7 in576 mm
- Snow a year
- 41 in104 cm
- Last spring freeze
- May 12
- First fall freeze
- Oct 4
- Heating degree days
- 7,911
- Cooling degree days
- 745
Freeze dates are medians (half of years earlier, half later). Degree days use a 65°F base; HVAC design temperatures here are −17°−27° (heating, 99%) and 99°37° (cooling, 1%).
Month by month
Gann Valley in January
Highs average 27°−3° and lows 4°−16°, with 0.32 in8.1 mm of precipitation and 8 in20 cm of snow in a typical January.
- Record high
- 65°18° (2012)
- Record low
- −37°−38° (2019)
- Heating degree days
- 1545
- Cooling degree days
- 0
Gann Valley in February
Highs average 31°0° and lows 9°−13°, with 0.61 in15 mm of precipitation and 9 in24 cm of snow in a typical February.
- Record high
- 71°22° (2017)
- Record low
- −29°−34° (2025)
- Heating degree days
- 1262
- Cooling degree days
- 0
Gann Valley in March
Highs average 45°7° and lows 19°−7°, with 0.98 in25 mm of precipitation and 5 in12 cm of snow in a typical March.
- Record high
- 89°32° (2012)
- Record low
- −25°−32° (2019)
- Heating degree days
- 1028
- Cooling degree days
- 1
Gann Valley in April
Highs average 58°14° and lows 31°0°, with 1.7 in43 mm of precipitation and 5 in14 cm of snow in a typical April.
- Record high
- 95°35° (2026)
- Record low
- 0°−18° (2014)
- Heating degree days
- 622
- Cooling degree days
- 1
Gann Valley in May
Highs average 70°21° and lows 44°7°, with 3.4 in85 mm of precipitation in a typical May.
- Record high
- 99°37° (2018)
- Record low
- 19°−7° (2020)
- Heating degree days
- 280
- Cooling degree days
- 30
Gann Valley in June
Highs average 80°26° and lows 56°13°, with 4.2 in107 mm of precipitation in a typical June.
- Record high
- 107°42° (2021)
- Record low
- 34°1° (2022)
- Heating degree days
- 54
- Cooling degree days
- 131
Gann Valley in July
Highs average 87°31° and lows 61°16°, with 3.2 in81 mm of precipitation in a typical July.
- Record high
- 109°43° (2017)
- Record low
- 40°4° (2025)
- Heating degree days
- 4
- Cooling degree days
- 283
Gann Valley in August
Highs average 85°29° and lows 58°15°, with 2.9 in74 mm of precipitation in a typical August.
- Record high
- 109°43° (2012)
- Record low
- 37°3° (2025)
- Heating degree days
- 20
- Cooling degree days
- 221
Gann Valley in September
Highs average 77°25° and lows 48°9°, with 2.8 in72 mm of precipitation in a typical September.
- Record high
- 101°38° (2022)
- Record low
- 25°−4° (2021)
- Heating degree days
- 151
- Cooling degree days
- 72
Gann Valley in OctoberThis month
Highs average 61°16° and lows 32°0°, with 1.6 in39 mm of precipitation and 1.8 in4.6 cm of snow in a typical October.
- Record high
- 93°34° (2015)
- Record low
- −3°−19° (2020)
- Heating degree days
- 574
- Cooling degree days
- 6
Gann Valley in November
Highs average 45°7° and lows 20°−7°, with 0.71 in18 mm of precipitation and 2.4 in6.1 cm of snow in a typical November.
- Record high
- 85°29° (2020)
- Record low
- −8°−22° (2011)
- Heating degree days
- 980
- Cooling degree days
- 0
Gann Valley in December
Highs average 31°−1° and lows 10°−12°, with 0.32 in8.1 mm of precipitation and 10 in24 cm of snow in a typical December.
- Record high
- 70°21° (2023)
- Record low
- −32°−36° (2016)
- Heating degree days
- 1391
- Cooling degree days
- 0