Meteo Zanzibar (Stone Town) in aprile

Zanzibar's forum is direct that April is the wettest month of the year, deep in the long rains that run mid-March through May, with many beach hotels closing entirely for the stretch. Regulars are split on how bad it actually is in practice — some report rain that comes and goes rather than lasting all day, others warn of genuinely torrential, relentless downpours — but the consensus is to shift a trip toward mid-May if the dates are flexible.

The long rains. I went once — cheap, empty, and it rained in hard bursts rather than all day, so it wasn't a write-off. But several hotels close outright in April, so check before you commit to the score.

Regulars describe this as the tail of the short rainy season sliding into the start of the dry one, with brief, periodic showers still a real possibility even as conditions turn generally sunnier, warmer and less humid overall. Our row backs the transitional read, 30C reading as a hot 32C, over 23.5C nights, with 37.9mm of rain across 9.7 days. Regulars are consistent the sea stays warm enough for a full day of swimming and snorkeling, and that crowds haven't built to the July-August peak yet, making this a genuinely relaxed window to visit. The sea holds a warm 27.5C. The record: humidity 78 percent, 10.5 hours of sun, a 20.2 kph wind and one of the cleanest air readings in this project, AQI 35.

July sits inside the dry season here, June through October, and regulars describe it getting cooler through those two months rather than staying flat - one of the driest stretches of the year, with rain rare enough that when a shower does arrive it rarely outlasts an hour. Our row backs both halves, 29.4C reading as 31C and only 22.9mm across 7.1 days. Wind is the one variable feature, described as notably strong on the east side of the island on a given day, which our column carries as a real 21.1 kph average. The sea stays warm regardless at 26.4C, good for snorkelling whatever the wind is doing on the beach. The record: humidity 76 percent, 10.8 hours of sun and AQI 32.

September sits inside the June-to-October dry season and regulars describe it simply as dry and pleasantly hot - our 21.9mm falls across 7.1 days, so those are showers rather than rain. The decision they want you to make is which coast. The kusi, the south-easterly, blows through September and October and the east side takes it; that is breezy relief to some people and a nuisance to others, and the west is the still, hotter alternative. Our 18.8 kph is an island average and hides that split. Days reach 30.6C but read as 34C at 75 percent humidity, with a 26.6C sea and nights that only fall to 22.1C. The record: 11.1 hours of sun and AQI 31, among the cleanest air in the collection.

Zanzibar forum regulars call October genuinely good — the tail of the dry season (June-October), still not too hot and not too rainy, with days around “80°F” and nights in the “70s°F.” The rains that do show up are described as short and non-monsoonal, clearing quickly, with the real wet season not properly arriving until November. One consistent framing across threads: October reads as “nice and warm but not too humid or sticky,” the last comfortable stretch before the short rains change the character of the island. Our record: 29.5°C days, 12 rain days, 80.5mm of rain and a 27.7°C sea — warm and swimmable with moderate rain, matching the “dry season's last good month” read.