So since the HC update I have played ~80 matches and I have not seen someone using bronze weather cards(fog,bitting frost and rain) most likely because they do not offer enough value for their provision cost and not offering synergy with units unlike in pre-HC GWENT where we had Foglets and Wild Hunt units synergies with weather which was a very good mechanic and also lore-friendly.
I think that they can make weather viable again if they added another interaction besides dealing damage to units for example ''Fog'' reducing ''Reach'' by 1 on a row that it's applied so for example you play a card with 2 reach upon placing it on that row the card's reach would be 1, also make weather Synergize with units(e.g. Wild Hunt with ''Bitting frost'').
I think that they can make weather viable again if they added another interaction besides dealing damage to units for example ''Fog'' reducing ''Reach'' by 1 on a row that it's applied so for example you play a card with 2 reach upon placing it on that row the card's reach would be 1, also make weather Synergize with units(e.g. Wild Hunt with ''Bitting frost'').