I think the weather would only put people off depending on where you are. If you have parking nearby then I can't see the rain putting anyone off, but if they know they've got a 5-10 min walk in a downpour I can imagine them thinking "nah".
Equally during the school hols I think if it's very hot, dad is likely to be persuaded to take the kids to the beach for the day, so no opportunity to pop out for a quickie to B&Q.