- Save on river cruises in 2025 with Avalon Waterways
- Book river cruises in Europe, Asia, Africa & Americas
- Filter deals by promotion, month, destination & more
Best time to visit Keystone
Find the best time to visit Keystone and plan your perfect trip in 2025/2026. Get holiday inspiration, weather guides, travel advice and find great deals.
- Best time to visit
- Weather by month
- 5-day weather forecast
- Destinations
- Travel advice
- Deals & discounts
Keystone by month
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Recommended for South Dakota
Expires at 23:59 on Wednesday 31st Dec 2025 · View all Avalon Waterways offers
When is the best time to visit Keystone?
The best time to visit Keystone is June, July and August based on the following average weather conditions.
Daily hours of sunshine = 10 hours or more [remove]
Change the criteria to reflect your weather preferences.
Which is the hottest month in Keystone?
The hottest time of year in Keystone is normally July. Expect maximum daytime temperatures to reach 29°C with moderate heat and humidity.
Which month has the most rain in Keystone?
In terms of rainfall, May is usually the wettest month in Keystone with 77mm on average. There are normally 12 days in May with some rain.
When is it sunniest in Keystone?
The sunniest time of year in Keystone is normally August with bright sunshine on average for 73% of daylight hours; that's 10 hours of sunshine per day.
Best time to visit
The weather guide for South Dakota (Keystone) shows long term weather averages processed from data supplied by CRU (University of East Anglia) & today's weather forecast provided by meteoblue. Find out more about our data sources.
Metric (°C / mm) | Imperial (°F / inches)
South Dakota travel features
Do you want to learn more about South Dakota? Read our latest features covering travel tips and insider destination guides on where to go and what to do in South Dakota.
We don't currently have any travel features on South Dakota. Discover more about holiday destinations around the world with this selection of general travel articles.
Be inspired
Get your weekly fix of holiday inspiration from some of the world's best travel writers plus save on your next trip with the latest exclusive offers
We promise not to share your details
Related posts
Popular travel offers
Explore holidays in the sun for less
- Beach holidays
- Family holidays
- City breaks
- Summer holidays
- Winter sun holidays
- Holiday offers
- Top travel brands
- Airlines & flights
- Discount hotels
- Airport parking deals
- TUI
- Jet2holidays
- easyJet holidays
- Love Holidays
- January sales
Airport parking
- Manchester Airport
- Stansted Airport
- Bristol Airport
- Luton Airport
- Birmingham Airport
- Edinburgh Airport
- Gatwick Airport
- Glasgow Airport
- Newcastle Airport
Airport lounges
- Manchester Airport
- Birmingham Airport
- Bristol Airport
- Edinburgh Airport
- Glasgow Airport
- Heathrow Airport
- Newcastle Airport
- Stansted Airport
- Gatwick Airport