Late September to mid-October is the peak — the maple, beech, and oak forests around the Finger Lakes turn gold and crimson, and the gorges look their best. Bring layers; mornings can be cold.
Summer (June to August) is warm and humid, good for swimming at Buttermilk and Treman, and the Ithaca Festival and weekend farmers market are in full swing. Winter (December to March) is properly cold and snowy, with the gorge trails closed for ice but excellent cross-country skiing nearby. Spring is the meltwater season — the falls are at their loudest and the trails muddy. The students are gone from late May to mid-August, which makes the town quieter but also slightly emptier.