The park is open year-round, but access may be difficult during the rainy season that lasts from June to September. For prime animal viewing, park rangers recommend visiting the park during the dry and hot season that ranges from February to late May, when wildlife regroup around permanent watering holes. Temperatures can be high, though, so pack appropriately.
Summer is the rainy season in Park W and the rains fill the rivers and waterholes, and the savannah looks lush. Wildlife viewing is difficult in the summer season because the vegetation is dense, making it harder to locate and observe animals.
Autumn is probably the most difficult time of the year to spot game in Park W because the grass is dense and high and access may be difficult. Birding is usually excellent during autumn in Park W.
If you are looking to make the most of your trip to Park W by combining a visit of the park with further exploration of West Africa, keep in mind that November through February are the coolest months (nights are quite pleasant).