About SunnyWhen
SunnyWhen helps travelers answer one question: when is the best time to go? Instead of anecdotes, we use long-term climate data — 30-year monthly averages of temperature and rainfall — to show what the weather is typically like in each destination, month by month.
Where the data comes from
Monthly climate normals are derived from CHELSA v2.1, a high-resolution (≈1 km) global climatology dataset covering 1981–2010, produced by the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL). We extract values at each destination's coordinates and present them as monthly averages.
How to read the numbers
- Average high / low — the typical daytime maximum and nighttime minimum for the month, averaged over 30 years. Individual days can be well above or below.
- Rainfall — total monthly precipitation. A high total can mean daily drizzle or a few intense downpours depending on the destination.
- Travel rating — a simple comfort heuristic combining daytime temperature and rainfall. It is a starting point, not a verdict on your trip: ski destinations are great in the cold, and monsoon season has its own charm.
Climate averages describe the past, not a forecast. Year-to-year variation — and a warming climate — mean actual conditions can differ.
Contact
Questions or corrections? See the contact page.