The Nias surf season runs roughly May to September, when the southern hemisphere swell hits Lagundri Bay most consistently. June and July are the peak months, with the right-hander pumping for days at a time and the losmen filling up; outside of these months the wave is less reliable but the bay is much quieter.
For non-surfers visiting the megalithic villages, April to October is the drier half of the year and the easier time to travel inland. Rain is possible at any time on Nias — this is equatorial Sumatra — but November to March is usually the wettest stretch.
Major Nias cultural festivals, when villages stage traditional dances and stone-jumping demonstrations, often coincide with Indonesian Independence Day (17 August) and with local Christian feasts in December.