forecast value, when in the hour? preceding or following?

[dodohjk]

This might be a very simple question but when does the forecast apply?
Is it the preceding hour or the following hour of the valid time?

For example if the forecast is at Anglesey airport in Wales, UK is
at 08:00Z Temp = 12C and Wind = 24KT

Does that apply to the following hour 08:00-->08:59Z,
or to the preceding hour 07:01-->08:00?
Would a perfect forecast vs observation be when the 07:50Z observation shows 12C 24KT or when the 08:50Z shows it?

[Korina]

@dodohjk Hello, the forecast is shown for that particular hour, so from 8:00 am to 9:00 am.