Expect cold weather through March, ice storms, snow, solitude, and MUCH frozen beauty. I found the winter to be the most memorable times on the trail, probably because they were the most challenging. I fully support an early start with one exception: if you are a fast hiker, you may get north too fast with an early start. The White Mountains were still snow covered in June and Katahdin might not be open if your hike is only 5 months long. If you plan on taking your time, no problem. If I’d do it all again, I’d start early February. I could go on and on about the pros and cons about starting early, send me an email if you need some help!
Hydro-Heidi