I've have mine down in all weathers, it's very frequently down too.
When it's cold I usually drive hood up until the heater is toasty then drop the hood so perhaps that helps.
I just make sure it folds properly (sometimes it can make an odd vertical sort of crease which will cause splits or holes done many times).
I think it's the wrong sort of creasing that causes splits (ie it should only fold horizontally and in a nice straight line with a gentle curve, anythings else will make sharper creases and cause weak spots).