Keystone, SD Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Keystone, a town in Pennington County, South Dakota.
This Afternoon
76°F
Slight Chance Showers And Thunderstorms
A slight chance of rain showers before 4pm, then a slight chance of showers and thunderstorms. Mostly sunny. High near 76, with temperatures falling to around 72 in the afternoon. East wind around 5 mph, with gusts as high as 16 mph. Chance of precipitation is 20%.
7-day forecast for Keystone
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 76°F | Slight Chance Showers And Thunderstorms | 5 mph E | 17% |
| Tonight | 57°F | Slight Chance Showers And Thunderstorms then Showers And Thunderstorms Likely | 0 to 3 mph W | 72% |
| Saturday | 64°F | Patchy Fog | 1 to 5 mph E | 72% |
| Saturday Night | 53°F | Showers And Thunderstorms Likely | 5 mph E | 74% |
| Sunday | 57°F | Showers And Thunderstorms | 5 mph E | 99% |
| Sunday Night | 51°F | Showers And Thunderstorms | 1 to 5 mph E | 97% |
| Monday | 59°F | Rain Showers Likely | 1 to 6 mph E | 65% |
| Monday Night | 52°F | Chance Rain Showers then Mostly Cloudy | 5 mph SE | 33% |
| Tuesday | 69°F | Mostly Sunny | 3 to 9 mph S | 14% |
| Tuesday Night | 56°F | Chance Rain Showers then Partly Cloudy | 3 to 7 mph S | 28% |
| Wednesday | 75°F | Mostly Sunny then Chance Showers And Thunderstorms | 6 mph S | 30% |
| Wednesday Night | 56°F | Slight Chance Showers And Thunderstorms then Mostly Clear | 3 mph SW | 21% |
| Thursday | 76°F | Sunny | 2 to 6 mph NE | 8% |
| Thursday Night | 56°F | Partly Cloudy | 3 mph S | 8% |
Forecast source: National Weather Service (api.weather.gov) for Keystone (43.895, -103.427). Updated through the day.
Growing snapshot for Keystone
Last spring frost
May 15
First fall frost
Oct 1
Growing season
138 days
Hardiness zone
5a
More local growing data for Keystone: nearby ZIP 57751 weather · frost dates · planting calendar · South Dakota frost dates
Nearby towns & communities
Caputa
Colonial Pine Hills
Cottonwood
Green Valley
Hill City
Johnson Siding
New Underwood
Quinn
Rapid City
Wall
Climate data from the nearest NOAA station, Mt Rushmore Nmem, Sd (1.6 mi from Keystone). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 18, 2026.