The best months to visit Slovenia are May and June. See monthly temperatures, rainfall and rain days (1991–2020 averages) to plan your trip.
Average daytime high and monthly rainfall in Slovenia: January 5°C / 60mm; February 10°C / 76mm; March 13°C / 77mm; April 16°C / 89mm; May 19°C / 101mm; June 23°C / 104mm; July 27°C / 96mm; August 28°C / 111mm; September 20°C / 127mm; October 16°C / 118mm; November 8°C / 124mm; December 5°C / 93mm.