If you are wondering what the weather will be like when you visit Vermont then read on but remember this is New England and the weather - as the old timers' say - "changes with the breeze". The weather in Vermont does have "averages" and northernern New England offers five distinct seasons.
Spring is probably the most diverse and unpredictable season. Spring in Vermont can mean a 24 inch snowfall or a beautiful 70 degree sunshiney day. Evenings are usually at or below freezing and the maple sap flows most often in early spring when days are warm (above freezing) and nights are cold. 
Summer Days are usually sunny and comfortable, low humidity is the norm. Temperatures reach the upper 70's to mid 80's. Light cloth
brings pleasant days and cool evenings. Days are usually sunny and comfortable, low humidity is the norm. Temperatures reach the upper 70's to mid 80's. Light clothing for days; sweaters or light jackets for evenings.
Autumn and Spring months typically have highs in the mid 50's with a variety of casual dress suitable. Evening lows can be below freezing, especially during early Spring and late Autumn. The warmest October on record was in 1971, average temperature was 54 degrees. The coldest October was in 1925 when the average was 39 degrees.
Winter is Vermont's longest season. Winter months require coats, heavy jackets, gloves and warm, dry boots. Below freezing temperatures are common from November - March.
Vermont receives much snowfall, with many areas getting more than 100 inches annually. This usually abundant snowfall contributes to the state's economy. Snowmobile trails and Vermont ski areas attract thousands of visitors annually. Annual precipitation is about 40 inches and is fairly evenly distributed throughout the state.
Vermont is rarely struck by hurricanes or tornadoes. So what the fifth season? Well, it is called Mud Season.