The Upper East Region has a single wet season from roughly May to September, when roads can become difficult and the landscape briefly greens up. The dry season, from October to April, is the easier time to travel. Harmattan winds from the Sahara blow dust across the region from December to February, reducing visibility and making the air hazy and dry.
The Bugum Fire Festival (also called the Chasing Away of Evil Spirits Festival) is held in January or February — the exact date follows the traditional Kassena-Nankana calendar and varies each year. It is Navrongo's most spectacular event: processions of torch-carriers move through the town after dark, and the atmosphere is vivid. Visitors are welcome and the whole thing feels genuinely communal rather than performed for outsiders.
The hottest months are March and April, before the rains arrive, when temperatures regularly exceed 40°C. If you are not acclimatised to serious heat, plan accordingly.