Can't comment on those specific airports, but there are loads of considerations for runway-in-use selection! If the surface wind is straight across, the upper wind (i.e. on the approach) might be different - on occasions, a bit of a headwind on approach with a slight tailwind at touchdown might enable a more stabilised approach, than the other way round. Then there are things like approach aids (ILS availability etc), lighting, rapid exit taxiways, which might favour one end over the other. You are absolutely right that the forecast is also a consideration if it's 50/50 at the time.
Most airports will have a "preferred runway-in-use" which might be for local noise restrictions, airport layout or airspace considerations (how complicated the interaction between deps and arrs is, or even between adjacent airports eg LCY and LHR). That's often the overriding decider, even to the point that the preferred runway would be used even with a slight tailwind.