The best months to visit Mongolia are May and September. See monthly temperatures, rainfall and rain days (1991–2020 averages) to plan your trip.
Average daytime high and monthly rainfall in Mongolia: January -11°C / 2mm; February -9°C / 3mm; March 4°C / 8mm; April 12°C / 16mm; May 22°C / 35mm; June 25°C / 56mm; July 28°C / 69mm; August 24°C / 70mm; September 18°C / 39mm; October 10°C / 15mm; November 2°C / 6mm; December -10°C / 2mm.