The weather in Maine should not be a problem in September, unless you plan to travel into the far northern, inland mountain area, and then it will most likely be fine. Yes, it can get a little cool at night, but that is refreshing. On the other hand, depending on where you travel, traffic can be an issue. The coastal route (Route 1) can be a long, slow ride anywhere from Kittery to Portland and beyond. We have been living in New England for 60 years and have a cottage in Ogunquit.
Neil, Lin, and our furry companions, Ashby and Cody. 06 National Surf Side.