I've had well over 50% cancelled so far, all to Wx, I've only been learning since July. Started booking 2 lessons per weekend, preferably at different times or ideally one Saturday and one Sunday, as less likely to loose them both!
I was wondering the other day if "statistically" there is a time in the day when you are least likely to have bad Wx. Eg in the Autumn (UK) is it often better early morning and deteriorates throughout the day?? Therefore booking at 9am or 10.30am more chance of flying?! (I haven't started studying Met yet...)