Queensbury has four sharp seasons. Summer (late June to August) is warm with daytime highs in the high 70s to mid 80s Fahrenheit, occasional thunderstorms, and the lakes warm enough to swim. It is the busiest season, when the Great Escape, Lake George and the Adirondacks all draw heavy crowds.
September is, for many, the best month: the air is cooler, the foliage is starting to turn, and the Adirondack Balloon Festival fills three or four days mid-month. The fall foliage peaks around the first or second week of October; the eastern Adirondacks are one of the best foliage areas in the country.
Winter brings serious cold (single digits to teens Fahrenheit), snowfall (60-80 inches a year on average) and the small-but-decent local skiing at West Mountain. Spring is wet and muddy — the "mud season" of late April and May is the locals' quiet time, and worth skipping unless you have a specific reason to be here.