Keystone, SD Weather & Growing Conditions
This Afternoon
55°F
Sunny
Sunny. High near 55, with temperatures falling to around 44 in the afternoon. Northwest wind around 2 mph.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 55°F | Sunny | 2 mph NW | 0% |
| Tonight | 33°F | Mostly Clear | 5 mph NW | 0% |
| Wednesday | 52°F | Partly Sunny | 6 mph N | 1% |
| Wednesday Night | 34°F | Mostly Cloudy | 3 to 7 mph NW | 1% |
| Thursday | 56°F | Sunny | 3 mph S | 0% |
| Thursday Night | 37°F | Partly Cloudy | 5 mph W | 0% |
| Friday | 55°F | Mostly Sunny | 0 to 5 mph N | 2% |
| Friday Night | 36°F | Mostly Clear | 2 to 7 mph W | 3% |
| Saturday | 58°F | Sunny | 2 to 7 mph NW | 3% |
| Saturday Night | 38°F | Mostly Clear | 3 to 7 mph W | 1% |
| Sunday | 66°F | Sunny | 7 mph W | 0% |
| Sunday Night | 46°F | Mostly Clear | 7 to 10 mph W | 0% |
| Monday | 60°F | Sunny | 2 to 6 mph N | 0% |
| Monday Night | 41°F | Partly Cloudy | 2 to 6 mph W | 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.