Best Time to Visit Mafia Island: Month-by-Month Guide (2026)

The best time to visit Mafia Island depends on what you are coming for. For scuba diving and snorkeling, the prime season is October through March, when the south monsoon (kusi) has ended, seas are calm, and visibility is at its best. For whale sharks specifically, the peak window is October through February, with November and December the most reliable months. October is the single strongest all-round month — calm seas, excellent diving, and whale sharks arriving together. June through September are the cooler months: the kusi brings swell that can make some sites challenging, but scuba diving and snorkeling remain possible, whale sharks are occasionally seen, and these are the best months for turtle hatchlings and for whale watching, particularly August and September. Avoid April and May, when the long rains (masika) rule out all marine activities.

Mafia Island has two distinct seasons that shape almost every activity. Here is what each month actually looks like on the ground.

Mafia Island seasons at a glance

Month-by-month breakdown

January & February — whale shark peak, warm & settled

These are strong months for whale shark encounters, which are at peak frequency around Kilindoni Bay and the outer atoll. Seas remain relatively calm after the December northeast monsoon transition, and dive visibility is good at 15–25 metres. Temperatures sit around 28–30°C. The lodge is popular during this period — book accommodation early.
Best for: Whale shark swimming, reef diving, birdwatching

March — still good diving, whale shark season winding down

March sits at the tail end of both the prime diving season and the whale shark season. Seas are generally still calm and visibility good, though conditions begin to soften toward late March as humidity rises ahead of the long rains. Early March is a strong time to visit — you may still encounter whale sharks and diving conditions remain solid. Accommodation rates often ease in March, making it good value.
Best for: Diving, late-season whale sharks, value travelers.

April & May — long rains

The Masika (long rains) makes this the least suitable period for a marine holiday. Seas are rough, dive sites are frequently inaccessible, and visibility drops to 5 meters or less. Eco Shamba Kilole Lodge is closed during April and May.

June & July — cooler season, Kusi swell, turtle hatchlings begin

une and July are the coolest months on Mafia Island, with dry air, low rainfall, and the south monsoon (kusi) blowing consistently. The kusi brings swell that makes some dive sites challenging, but scuba diving and snorkeling remain possible — our team selects sites according to daily conditions. Whale sharks are occasionally sighted during this period. These months mark the beginning of turtle hatchling season, with hawksbill and green sea turtles emerging on the beaches surrounding the Marine Park. The lodge is quiet and uncrowded, and rates are often more favourable.
Best for: Turtle hatchlings, birdwatching, quiet stays, budget-conscious travelers. Diving and snorkeling possible on suitable days.

August & September — turtle hatchlings and whale watching peak

August and September are the best months on Mafia Island for two specific experiences: turtle hatchlings and whale watching. Hawksbill and green sea turtles hatch in significant numbers during this window, and whales are reliably present in the surrounding waters. The kusi swell eases through this period and diving conditions gradually improve — scuba diving and snorkeling remain possible, with sites selected daily based on conditions. Whale sharks are occasionally encountered. By late September the sea is calming meaningfully and October’s prime season is close. The lodge is still quiet relative to the October–March peak.
Best for: Turtle hatchlings, whale watching, birdwatching, guests who want a less crowded stay with improving marine conditions.
Diving: Possible throughout, conditions improving steadily toward October.

October — the strongest all-round month

October is where everything converges. The kusi has fully eased, seas are calm, visibility is excellent, and whale sharks begin arriving in the bay. Water temperature climbs back toward 28°C. The lodge fills faster in October than any other month — book early. Note that whale shark encounters are always a snorkeling experience — you swim on the surface alongside them, not scuba diving.

Best for: First-time visitors. Divers and snorkelers. Whale shark swimming. Families. Photography.

November — whale shark peak, short rains begin

Whale shark activity reaches its highest frequency in November and December. The short rains (vuli) bring occasional afternoon showers but rarely disrupt morning dive excursions. Visibility remains good at 15–20 metres. The rains also green up the botanical garden dramatically — the property looks its most lush during this month.
Best for: Whale shark swimming, reef diving, birdwatching, guests who don’t mind brief afternoon rain.

December — festive season, whale sharks, warm water

December combines peak whale shark activity with warm water (28–29°C), low rainfall, and the festive atmosphere of the year-end travel period. It is one of our busiest months. Visibility is consistently good. Book well in advance.
Best for: Families, couples, whale shark swimming, festive travel.

Sea turtle nesting season on Mafia Island

Hawksbill and green sea turtles nest on the beaches surrounding the Mafia Island Marine Park primarily during March and April. Hatchlings emerge approximately 60 days after nesting, making June and July the peak months for turtle hatchlings, with significant numbers continuing through August and September. Guests visiting during the Kusi season have a unique wildlife experience that is simply not available during the more popular October–March diving season.

Birdwatching seasons on Mafia Island

The 13-acre botanical garden at Eco Shamba Kilole Lodge hosts over 30 resident bird species year-round, including the Collared Sunbird, African Paradise Flycatcher, and Yellow-billed Kite. Birdwatching is rewarding in every month — even during the Kusi season you can spot more than 30 species on a morning walk. The most productive period is September through March, when Palearctic migratory birds returning from Europe join the resident species, significantly expanding what you can see. Early mornings offer the clearest sightings year-round.

Summary: which month is right for you?

• You want the best scuba diving and snorkeling: October through March — calm seas, good visibility, no kusi swell
• You want whale shark swimming: October through February — peak in November and December; occasional sightings June–September
• You want turtle hatchlings: June and July peak, continuing through August and September
• You want whale watching: August and September
• You want the best birdwatching: September through March — resident species plus European migrants
• You want a quiet, uncrowded stay: June through September — cooler, fewer guests
• Avoid entirely: April and May — the lodge is closed during the masika long rains.

Still unsure? Contact us directly — we are happy to advise based on your priorities and the current season.