I've started having a problem with condensation build up recently. Both front and rear seats are getting damp and a white powdery mould is forming on the fabric. I can't find any leaks, all the seals are fine, the carpets are dry too. I don't use the car every day so was thinking perhaps the dampness was due to the sun warming the car during the day and then the temperature dropping overnight causing condensation..... Has anyone had this problem at all? I have a 55 plate wrx station wagon...

Does sound odd, i'd get some silica gell or a damp trap form asda and stick it in, have you had a look in the wheel well ? On wagons it usually creeps in and pools there

Hello mate, I would also check under the carpets, a lot of times in other cars you can have a big thick layer of padding/sound deadening under there and the water doesn't get high enough to wet the carpet 

Are you getting wet inside the Windows 

Thanks for the replies. No wet inside the windows, nor in the spare wheel well. I think it's because of the cold nights and then some sun during the day causing the dampness.