The best months to visit Portugal are June and May. See monthly temperatures, rainfall and rain days (1991–2020 averages) to plan your trip.
Average daytime high and monthly rainfall in Portugal: January 15°C / 68mm; February 17°C / 52mm; March 17°C / 53mm; April 22°C / 53mm; May 24°C / 44mm; June 27°C / 11mm; July 33°C / 2mm; August 33°C / 4mm; September 28°C / 29mm; October 22°C / 78mm; November 19°C / 84mm; December 15°C / 79mm.