@idefix37 If I am to check weather information of Japan, I would usually use sites like https://weathernews.jp/ and https://tenki.jp/ which offer a lot more layers of information than Windy. For example, they provide forecast maps of spread of allergy-triggering pollen, the time of sakura blossom and when the leaves turn red, apparent temperature, seasonal forecast, easiness to observe starry sky, flash rain warning, upcoming hours radar forecast, and so on.
p.s. talking about mountainous area, I think Taiwan and Luzon and South Korea around the area also have somewhat comparable terrain despite different in each of their own ways. If a model of its kind is to be adopted I think these area should also be considered.