The Central African Republic has a tropical climate split sharply between a wet and a dry season, modulated by latitude. The south is wetter and more humid; the north slides into Sahel conditions.
Dry season (November–March) is the only practical time for travel. Roads — what passes for them — are usable, river crossings are manageable, and the gorilla and elephant viewing in the Dzanga-Sangha rainforest reserve is at its best because animals concentrate at predictable waterholes and bais. Temperatures climb steadily, reaching the high 30s by March.
Hot lead-up to the rains (March–April) is dusty, hazy with Harmattan dust early in the period, and hot. Wildlife viewing is still possible but uncomfortable.
Wet season (May–October) brings heavy rains, washed-out roads, and impossible bush travel. Most lodges and reserves close.
Security is the bigger planning factor. Most of the country has active armed groups; consult your foreign office advisory before booking anything. Visits to Dzanga-Sangha are usually flown in from Bangui or Cameroon and handled through specialist operators who manage permits and logistics.