Bansko has two clear seasons and not much in between. The ski season runs from around 20 December to the end of March, peaking in February when snow is most reliable and queues at the gondola are at their worst. Christmas–New Year is busy and expensive; the second half of January is often the sweet spot — good snow, fewer Russians and Israelis than peak February, lower hotel prices.
The summer hiking season is shorter — late June through early October. July and August are warm in town but cool on the peaks, with afternoon thunderstorms common; September is the most reliable month for high-altitude walks. April, May, November and early December are the shoulder periods when neither the lifts nor the hiking huts are properly open and Bansko is a quiet, slightly closed-feeling town — go elsewhere.