Unguja sits six degrees south of the equator, so it is hot all year: daytime highs stay between 28 °C and 34 °C and the sea never drops below about 25 °C. What actually changes through the year is rain, wind and humidity.
Two monsoons govern the island. The kaskazi blows from the north-east from roughly December to March — hotter, more humid, calmer seas. The kusi comes from the south-east from June to September — cooler, breezier, drier and the most comfortable time to be here.
Between them come the rains: a long wet season in April and May, and a shorter, lighter one in November.
The four seasons of a Zanzibar year
The cool dry season
The best all-round window. Dry, breezy, warm rather than hot, low humidity and excellent visibility underwater. It is also the busiest and most expensive stretch, overlapping with the European summer and the Serengeti migration.
Best overall — book early
The hot dry season
Hot and humid with calm seas and lots of sun, punctuated by short sharp showers. Christmas and New Year are the single busiest and priciest fortnight of the year; late January and February are quieter and still excellent.
Great sea conditions, peak prices at Christmas
The long rains
The real wet season: heavy, sustained afternoon rain, high humidity, rough seas and a lot of hotels and boat operators closed. Prices collapse. If you can handle the risk, May in particular can be a bargain with usable weather.
Cheapest — and genuinely wet
The short rains
A shoulder season with brief showers rather than washouts, warm seas and far fewer people. Late October is one of the most underrated times to be here.
Best value with reliable weather
Zanzibar month by month
Typical conditions and what each month is good for.
| Month | Weather | Sea & wind | Good for |
|---|---|---|---|
| January | Hot, humid, short showers | Calm, warm | Sunshine, diving, families |
| February | Hottest month, ~34 °C | Very calm, clear | Best diving visibility, honeymoons |
| March | Hot, humidity building | Calm, rain increasing | Value before the rains |
| April | Long rains, heaviest month | Rough, murky | Bargain hunters only |
| May | Rain easing late in month | Choppy, improving | Low prices, quiet beaches |
| June | Dry, breezy, ~29 °C | Kusi wind builds | Kitesurfing, walking, everything |
| July | Dry and pleasant | Windy, clear | Peak season, kitesurfing |
| August | Dry, comfortable | Windy, clear | Peak season, Sauti za Busara aside |
| September | Dry, warming again | Wind easing | Diving, whale sharks off Mafia |
| October | Warm, occasional showers | Calming, clear | Best value, few crowds |
| November | Short rains, brief showers | Calm between showers | Quiet beaches, low prices |
| December | Hot, humid, sunny | Calm, warm | Sun — but book Christmas early |
Pick your month by what you want
Best weather overall
June to September. Dry, breezy and comfortable, with the clearest water of the year in the second half of the window.
Best diving and snorkelling
February to March and September to October, when the sea is calmest and visibility at Mnemba is at its best.
Best for kitesurfing
June to September for the strong, reliable kusi, and December to February for the lighter kaskazi.
Best value
October and November, or May if you will accept some rain. Room rates can be half the July figure.
Fewest people
April, May and November. Some hotels close in April, but the beaches are yours.
Avoid if you can
April, unless the price is the point. And Christmas–New Year, unless you book many months ahead.
