Data and method
Last updated: 4 October 2026
Overview
Pohoda is built on the normal climate: typical weather at each place for each fortnight of the year. The optional seasonal forecast adjusts those normal values for the next three months, only where the forecast models have demonstrated skill.
1. The normal climate
The base layer is ERA5, the Copernicus and ECMWF reanalysis, for 1996 to 2025. Each place is described by its seasonal cycle plus a gentle long-term trend. Values are averaged into 26 fortnights per year at about 28 km resolution. Variables: temperature (highest, lowest, average), rain, wind, cloud, sunshine, wet, frost and snow days, and sea temperature.
The map colours, the match score and the best-time tables use these normal values.
2. The seasonal forecast
A seasonal forecast gives the lean of the coming months: warmer or cooler, wetter or drier than normal. It does not forecast individual days. Pohoda uses the Copernicus Climate Change Service multi-model forecast from five centres (ECMWF, Météo-France, DWD, ECCC, CMCC). It covers up to three months ahead and is refreshed monthly, around the 5th.
Thirds, not degrees
The forecast is expressed as odds for three equal groups. For one month at one place, the last 24 years are sorted into the coolest (or driest) third, the middle third and the warmest (or wettest) third. In a typical year each group has a one in three chance. The forecast states how those odds shift, for example a 55% chance of the warm third.
Is the forecast any good here?
Seasonal forecasts are skilful in some places and seasons and not in others. Each model is tested against 1993 to 2016: for each place, do its forecasts beat guessing the average? This gives a skill score per place, tested so that chance results do not count. Where no skill is shown, the forecast is not used.
Skill falls with lead time and is higher for temperature than for rain. Rain has skill mainly in the tropics, where patterns such as El Niño steer rainfall.
How the numbers change
Where the forecast has skill, the normal value is shifted toward the forecast, scaled by confidence.
21.0 °C plus 0.9 °C shows 21.9 °C.
40 mm times 1.12 shows about 45 mm. The factor is the odds-weighted average of how much wetter or drier each third has been at that place historically.
Clicking a place shows a note in the popup stating what the forecast changed there. Where there is no reliable signal, the note says so and values are unchanged. Adjusted fortnights are shaded on the slider and in the timeseries; darker means higher confidence.
What this cannot do
- It does not forecast individual days, only the lean of a month.
- Reliability falls with lead time.
- Beyond three months everything is the normal climate.
- Rain adjustments are approximate: the thirds come from 24 years of ERA5 and stand in for the models' own thirds.
- If a monthly release is late, the sidebar states which release is in use.
The raw forecast maps
The unadjusted forecast layers (odds and anomalies, with a confidence view) are at pohoda.app/?outlook=global&raw=1.
Sources
- ERA5 reanalysis. Hersbach et al., Copernicus Climate Change Service (C3S) Climate Data Store, doi:10.24381/cds.adbb2d47.
- Seasonal forecasts. C3S multi-system seasonal forecast (ECMWF SEAS5, Météo-France, DWD, ECCC, CMCC), Copernicus Climate Data Store.
- Crowd seasonality. Eurostat tourist nights and national statistics, described in the About panel.
Contains modified Copernicus Climate Change Service information (2026). Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains. Pohoda is a planning aid and not a forecast service: check official forecasts before you travel.
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