Everything you need to know about Zanzibar's tropical climate, temperatures, rainfall, wind, sea conditions, and how each season affects your tour experience.
Zanzibar sits just 6 degrees south of the equator, giving it a warm tropical climate year-round. Sea temperatures rarely drop below 24°C, air temperatures range from 22°C to 34°C depending on season, and the island receives around 1,500mm of annual rainfall concentrated in two monsoon periods.
Temperature
Zanzibar is consistently warm throughout the year. The coolest months are June to August, with temperatures between 22–28°C ideal beach weather. The hottest months are November to March, when temperatures can reach 32–35°C. Coastal breezes make the heat manageable, and the ocean is always nearby for cooling off.
The Kaskazi & Kusi Monsoons
Zanzibar's weather is governed by two monsoon systems. The Kaskazi (northeast monsoon) blows from November to March, bringing warm, dry weather to the north coast and calmer seas on the eastern side. The Kusi (southeast monsoon) blows from May to September, bringing the cooler, drier weather of the long dry season.
Understanding which monsoon is active helps predict sea conditions for water-based tours. During the Kusi season, the east coast can experience stronger swells, while the west coast (Stone Town, Nungwi) remains calmer. During Kaskazi, conditions reverse.
Ocean Conditions for Snorkeling & Water Sports
The best snorkeling visibility is during the dry seasons when there is minimal runoff affecting water clarity. Visibility at Mnemba Atoll regularly exceeds 25–30 metres between July and February. During the wet season, visibility can drop to 5–10 metres due to increased particulate matter in the water, though the marine life itself is just as abundant.
Sea temperature is an important consideration for comfort. Water temperatures range from 26°C in July to 30°C in January, making it consistently warm enough to snorkel without a wetsuit year-round.