The weather in Keystone in September is hot. The average temperatures are between 21°C and 27°C.
As it is almost never rain during September in Keystone the weather is perfect for hanging out outside and exploring all that Keystone has to offer.
Our weather forecast can give you a great sense of what weather to expect in Keystone in September 2025.
If you’re planning to visit Keystone in the near future, we highly recommend that you review the 14 day weather forecast for Keystone before you arrive.
Temperatures
27° / 21°
Rainy Days
0
Snowy Days
0
Dry Days
30
Rainfall
12
mm
Sun Hours
11.3
Hrs
