Outdoor grow problem

I am growing 1 plant outside which appears to be a female. It has been growing since April and was full and beautiful until last week. What happened is that the plant looks great but for some reason on the top all around the plant it is starting to wilt. Only about 10% of the plant is wilting and it is the parts of the plant that will produce the most bud. I will post a pic later but does anyone have any ideas?