Karakol has a genuine four-season mountain climate, and the "best" time depends on what you want to do.
Warm days, all high-altitude routes open (Song-Kul, Ala-Kul, Tash-Rabat), yurt camps operating, paragliding conditions at their best. This is when most visitors come, and it's the only window for the highest-altitude tours.
Fewer crowds, still-open lower-altitude tours (Jeti-Oguz, Altyn Arashan, city tours), cooler but manageable weather. Good value, though some high-altitude routes may already be closed by snow.
Song-Kul and Ala-Kul are closed by snow. Karakol itself is still very much worth visiting — Jeti-Oguz in snow is genuinely beautiful, and it's the season for our Winter VIP route. Karakol is also a short drive from Kyrgyzstan's main ski resort.
If you specifically want Song-Kul or Ala-Kul, plan June-September. For everything else, May through October all work well — just message us your dates and we'll tell you exactly what's open.