Keystone, SD Weather & Growing Conditions
Overnight
27°F
Mostly Clear
Mostly clear. Low around 27, with temperatures rising to around 35 overnight. West wind around 5 mph.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 27°F | Mostly Clear | 5 mph W | 0% |
| Wednesday | 52°F | Mostly Sunny | 3 to 7 mph N | 0% |
| Wednesday Night | 34°F | Partly Cloudy | 6 mph NW | 0% |
| Thursday | 54°F | Sunny | 3 mph S | 0% |
| Thursday Night | 37°F | Partly Cloudy | 6 mph W | 0% |
| Friday | 54°F | Mostly Sunny | 0 to 5 mph N | 1% |
| Friday Night | 37°F | Mostly Clear | 1 to 7 mph W | 0% |
| Saturday | 59°F | Sunny | 2 to 7 mph NW | 0% |
| Saturday Night | 38°F | Mostly Clear | 3 to 7 mph W | 0% |
| Sunday | 66°F | Sunny | 7 mph W | 0% |
| Sunday Night | 45°F | Mostly Clear | 6 to 9 mph W | 0% |
| Monday | 60°F | Sunny | 0 to 5 mph N | 0% |
| Monday Night | 40°F | Partly Cloudy | 0 to 5 mph W | 0% |
| Tuesday | 61°F | Mostly Sunny | 1 to 5 mph SW | 0% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Keystone, SD
Last spring frost
May 15
First fall frost
Oct 1
Growing season
138 days
Hardiness zone
5a
Explore more for Keystone, SD: full frost dates · planting calendar · South Dakota frost dates
Climate data from the nearest NOAA station, Mt Rushmore Nmem, Sd (1.6 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.