Ruidoso is genuinely a year-round destination, but the character changes dramatically by season.
Winter (December–March) brings skiing at Ski Apache. Snow is reliable at elevation, though the ski season is shorter than northern resorts. The town is busy on weekends when skiers come up from El Paso and Albuquerque.
Summer (June–August) is peak season. Temperatures hover around 75–80°F while the desert below bakes at 100°F or more. Hiking, mountain biking, and fishing are all excellent. This is also horse-racing season, and the Labor Day Futurity weekend is the single biggest event of the year — book months in advance.
Spring and Fall are quieter and pleasant. Fall brings aspen color on the upper slopes, usually peaking in early to mid-October.
Avoid the town on major holiday weekends unless you've already secured accommodation — it fills up completely.