How we calculate festival weather odds
We take the dates of every past edition from Wikidata and Wikipedia and read hourly ERA5 reanalysis (1991–2025) at the event site; each number on the site is a count of past editions or days.
Which events
Large European music festivals, city and folk festivals, marathons and half marathons with at least 10 dated editions from 1991 to 2025, found through Wikidata (number of Wikipedia language versions) and a list of well-known events. Events that ended before 2019 are left out.
Dates of past editions
From Wikidata items of each edition (start, end or point in time, precision of a day) and from tables and lists in Wikipedia articles in up to six languages. When the two disagree for a race, the date given by at least two Wikipedia language versions wins. Cancelled editions (for example 2020–21) and fallow years are not counted.
One edition window
A race counts on its race day. A festival counts on its official programme days. Where a source lists camping or warm-up days, or a second weekend, we keep the last N days, where N is the festival's usual length; this keeps every edition comparable.
Venue changes
If Wikidata dates a different venue more than 10 km away, or we verified a move by hand (Rock am Ring at Mendig in 2015–16), the weather of those editions is taken at the other site and the page says so.
Weather
Hourly ERA5 reanalysis (Copernicus Climate Change Service), read from the Open-Meteo mirror on AWS, for the nearest land cell of the 0.25° grid (about 25 km). Days are local calendar days. A rainy day has at least 1 mm; mud means at least 40 mm over the festival and the week before; a hot day reaches 30 °C. For races: temperature at 9:00 local time and rain from 08:00 to 14:00 (at least 0.5 mm). For Christmas markets: evenings from 17:00 to 21:00, frost when any hour is below 0 °C, wet with at least 0.5 mm, snowfall with at least 0.2 mm of snow water.
Usual dates
The climate of the usual dates uses the median start day of past editions and the festival's usual length (races: the median race day ± 3 days), on every year 1991–2025, whether or not the event took place.
Limits
ERA5 slightly overstates how often light rain falls (by about 5–7 percentage points against stations) and understates daytime highs by about 1–2.5 °C; it does not see very local showers. These are statistics of past weather, not a forecast.