Accra is hot and humid all year, with temperatures hovering between 25 and 32 degrees. The two rainy seasons — a long one from April to June and a shorter one in September and October — bring sharp tropical downpours rather than days of grey drizzle, so they don't necessarily ruin a trip. The driest, most pleasant months are November through February.
In the harmattan season, roughly December through February, a dry wind off the Sahara fills the air with fine red dust that hazes the sun and makes for spectacular sunsets but plays havoc with anyone prone to allergies or asthma. Bring lip balm and don't expect a clear horizon.
The two events worth timing a trip around are the Homowo Festival, in August or September, when the Ga people celebrate their pre-colonial harvest with parades, drumming, and the throwing of kpokpoi (a maize and palm-oil dish) onto the streets to remember an ancient famine; and Chale Wote, a street art and music festival that takes over Jamestown for a weekend every August. Independence Day on 6 March brings parades and ceremonies on Black Star Square.