After 8 weeks you are fine. If you are reading this BEFORE your hair transplant - the answer is different! Avoid Aspirin at least a week before the surgery to reduce bleeding during the procedure.Good luck!
You cannot change the direction of transplanted hairs. This is very unfortunate but it is too late. It is time to visit a doctor for an examination and treatment options.
After eight months post op, your transplanted hairs have either taken or not taken. This actually happened in the first few days after your surgery. So at this point weather would not affect your transplanted hair's growth or success.
