Summers are often hot and humid, with average temperatures in the high 80 or 90 degrees fahrenheit; autumn and spring are mild and pleasant; winters are rarely harsh, with average temperatures about 30 degrees Fahrenheit.
Maine ocean islands provide the only nesting sites for Atlantic puffins in the United States. Eastern Egg Rock in the midcoast region, Seal Island and Matinicus Rock at the mouth of Penobscot Bay, and Machias Seal Island and Petit Manan Island off the downeast coast provide habitat for more than 4,000 puffins each summer.