This is not Windy site which updates the weather forecast but the model you use. Each model has different interval. For instance, GFS updates the forecast every 6h so 4 times a day when ECMWF (IFS) updates every 12h so 2 times a day. When a model is chosen, you can check with your computer or your smartphone when the next update will be
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As you can see here above, it is GFS, interval 6-7h and next update is indicated, in 5h41m