July to October is the best weather window on the coast. Usually after the Portland Rose Festival in June.

Whale watching in the winter and spring months on the coast.
Snow Ski October to late May, early June.

Festivals are mid summer to late Fall - Wine, Harvest, ect.

Everything is in full bloom April - May to November.
I have to mow the grass year round

The Eastern and Southern parts of the state hit decent spring weather late March to April.