Keystone weather in September 2019

• 23
  23°C max day temperature
• 9
  9 hours of sunshine per day
• 8
  8 days with some rainfall
• 6
  6°C min night temperature
• 12
  12 hours of daylight per day
• 0
  No heat & humidity
• 32
  32 mm of monthly rainfall
• 6
  6 (High) UV index

Going to Keystone? Find the best month to visit Keystone based on the weather.

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Expect 23°C daytime maximum temperatures in the shade with on average 9 hours of sunshine per day in Keystone in September. Check more long-term weather averages for Keystone in September before you book your next holiday to South Dakota in 2019/2020.

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The September weather guide for Keystone, South Dakota shows long term weather averages processed from data supplied by CRU (University of East Anglia), the Met Office & the Netherlands Meteorological Institute. Find out more about our data sources.

Metric (°C / mm)  |  Imperial (°F / inches)

Guide to Keystone weather in September

The average maximum daytime temperature in Keystone in September is a warm 23°C (73°F). The average night-time temperature is usually a cold 6°C (43°F). There are usually 9 hours of bright sunshine each day, which represents 68% of the 12 hours of daylight.

Expect 32mm (1.3 inches) of rainfall across the whole of September with 8 days with some rain falling. Maximum UV levels will be high (6 UV index) at midday when the skies are clear.

Keystone sunrise & sunset times for September 2019

Browse the sunrise & sunset times for Keystone in September 2019. Select a month to view Keystone sunrise & sunset times for the next twelve months.

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More South Dakota destinations

• Aberdeen
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