Keystone (SD) Weather & Climate: Best Time to Visit
Average temperatures, rainfall, sunshine and the best time to visit Keystone.
Climate overview of Keystone
Keystone, South Dakota, United States of America, sees big temperature differences between seasons, with July peaking at 28°C (82°F) and February dropping to 3°C (37°F).
Keystone sees a moderate amount of rain/snowfall, totalling around 536 mm (21 in) per year. It experiences a distinct dry season from November to March, with warm summers and cold winters, creating some seasonal variation.
Keystone Weather by Month
Pick a month to see the average temperature, rainfall and sunshine in Keystone - and find the best time to visit.
Monthly Temperature in Keystone
Visitors to Keystone can expect significant temperature changes throughout the year. Average maximum daytime temperatures range from a comfortable 28°C (82°F) in July, the warmest time of the year, to a chilly 3°C (37°F) during cooler months like February.
At night, you can expect temperatures ranging from 14°C (57°F) in July to around -10°C (14°F) during February.
Check out our detailed temperature page for more information.
Temperature ranges by month
Rainfall in Keystone
Generally, Keystone experiences moderate precipitation patterns, averaging 536 mm (21 in) yearly. Significant seasonal changes in precipitation occur throughout the year. In the wettest month, May it receives high rainfall, averaging 114 mm (4.5 in) of precipitation, recorded across 15 rainy days. In contrast, the driest month January brings less snowfall, with 8.4 mm (0.3 in) over 6 snowy days. For more details, please visit our Keystone Precipitation page.
The mean monthly precipitation over the year, including rain, hail, and snow
The average number of days each month with precipitation
Best Time to Visit Keystone
Monthly ratings reflect general weather comfort, based on daytime temperature and rainfall. Swimming and winter conditions are highlighted separately where relevant.
- Best overall: June, July, August and September
- Warmest weather: July and August
- Wettest months: April, May, June, July and August, when rainfall is highest.
- Seasonal pattern: A distinct dry season from November to March, with warm summers and cold winters
- Coldest conditions: February, with freezing nights around -10°C (14°F).
Frequently asked questions about the climate in Keystone
What is the best time to visit Keystone?
June, July, August and September typically offer the most optimal weather in Keystone. In contrast, January, February and December tend to have less optimal conditions. Keystone has a distinct dry season from November to March, with warm summers and cold winters.
What temperatures can I expect in Keystone?
Daytime highs range from 3°C (37°F) in February to 28°C (82°F) in July. Nighttime lows range from -10°C (14°F) to 14°C (57°F). Temperatures vary considerably through the year.
How much rain does Keystone get?
Annual rainfall is around 536 mm (21 in). May is the wettest month with 114 mm (4.5 in), while January is the driest with 8.4 mm (0.3 in).
Keystone 3-Day Forecast
Keystone on the map
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