@simjoubert
OK but this app is not the App of Windy.com !

https://community.windy.com/topic/3756/warning-russian-windy-app-uses-our-name-and-want-you-to-pay-for-nothing

The true Windy App is available on the App Store, with the same logo as Windy.com and is free. On the true Windy App there is no « 1h/3h switch button » because the ECMWF provide their data with a 3h step.
(Je suppose que l’application russe fait simplement une interpolation des données d’origine, du moins pour le modèle de l’ECMWF)