The best time to dive Komodo: September or October?

Two seas in one park, and the month they overlap

At Batu Bolong the current arrives before you do. You drop into 28°C water on the sheltered side of a pinnacle, tuck in behind the rock, and watch fusiliers stack up like traffic. ^{2, 3} 4 to 5 hours south by boat, the same park runs 20 to 25°C, and the thermoclines there come as standard. ²

One park, two seas. North and central Komodo dive well from roughly April to November and peak in July and August. The south faces the open Indian Ocean and the full fetch of the southeast monsoon, which closes it through July and August and reopens it around October. ^{2, 1} September and October are the seam between the two.

Every figure comes from a dive operator's own conditions page, Indonesia's meteorological agency, or a peer-reviewed count of 1,085 photo-identified manta rays in the park. ⁸ If the bill is your question instead, what a Komodo trip costs in 2026 has the park fees and the boat fares.

Is September a good month to dive Komodo?

Four sources publish September and October figures, one of them twice. They agree on the shape of the month and differ by about 3°C on the reading.

Yes, and two of the three operators that write it up rank it above August for crowds and price. Komodo Resort's own month table reads 25°C and 15 to 25m of visibility for September, with reliable big-fish sites. Scuba Republic's September write-up reads 27 to 28°C and 25 to 30m. Dragon Dive Komodo calls it the sweet spot and its top choice for 2026, at about 25 to 27°C. ^{3, 4, 5}

The satellite series moves the other way from the operators' thermometers. It puts September at 27.3°C and October at 28.6°C, a rise of 1.3°C, against a yearly low of 26.7°C in July and August and a high of 30.0°C in December, a swing of 3.3°C across the year. ⁹ That is a surface average for the whole area. The suit you rent depends on the zone.

September also costs less. Scuba Republic notes that many hotels drop their rates after August and that flights and liveaboard berths open up. ⁴ If you are weighing a boat against a bed on shore, the liveaboard and shore-diving cost comparison sets the two side by side.

What is Komodo's water temperature?

Two answers, and the honest one names the zone first. The park runs two thermometers about 9°C apart.

North and central Komodo sit at 27 to 29°C nearly year round, warmest in July and August. South Komodo drops to 20 to 25°C, and colder at depth, where cold upwelling meets the Indonesian Throughflow squeezing 15 to 20 Sverdrups of Pacific water through the Sape and Linta straits. ¹ One park, two suits.

The spread is the planning fact. Take 29°C at the top of the north's range against 20°C at the bottom of the south's and you get a 9°C difference inside one national park. ¹ Then add the thermocline. Komodo Resort's October article puts it at 3 to 4°C between roughly 15 and 22 metres in the south, so 20°C at the surface reads 16°C on your computer at depth. ²

Which months have the best visibility?

April, May, June and October are the blue-water months on the northern pinnacles, the four with a 20m floor, by the reckoning of the one operator that publishes month-by-month figures. May tops it at 20 to 30m. October reads 20 to 25m. September shares October's ceiling and sits 5m lower at the floor. ³

September's own range spans 10m, from 15m to 25m, which is the width of a month that can hand you a blue day or a green one. ³ The wider pattern across operators is steadier: 15 to 30m is what Komodo gives most of the year, because the current that stirs the reef also clears it. ⁷

Why the current is the reason the reefs are crowded

The same flow that makes Castle Rock a drift dive is what feeds everything on it.

Komodo sits in the path of the Indonesian Throughflow, the river of Pacific water forced toward the Indian Ocean, and it speeds up through the narrow channels between Komodo, Rinca and Gili Lawa. Twice-daily tides amplify it. In the June to August southeast monsoon, surface current in the straits reaches 7 to 8 knots. ^{1, 7}

That movement pulls cold, nutrient-rich water onto the reef. Corals grow fat, anthias swarm, and the big animals gather where the food is. It also keeps visibility at 15 to 30m for most of the year. ⁷ So you drift with it and hook into bare rock when you want to stop. The current is the product, and the diving is built around reading the tide.

The same operator publishes goal-based shortcuts that line up with the table. June through September is its pick for sharks, because the strong exchange pulls nutrients past Castle Rock, Crystal Rock and Shotgun. November through February is its pick for mantas. ³ September and October straddle the handover.

Where are the mantas in September and October?

At the central cleaning stations, all year, in numbers that build through October. Karang Makassar and Mawan hold reef mantas even in the thin July and August window. The trains of twenty, thirty animals and more are most reliably seen from roughly September through May, and December to February is the standout stretch. October sits on the rising edge of that curve. ²

• Karang Makassar, better known as Manta Point, 5 to 18m and open to Open Water divers. Reef mantas year round, with the 20 to 30 animal aggregations concentrated from September through May. ^{2, 6}
• Mawan, 8 to 20m, the second central cleaning station, on the same calendar and the same certification level. ⁶
• Manta Alley in the south, 10 to 25m and rated Advanced, for reef mantas and the rarer oceanic manta at up to 7m across against 3 to 5m for a reef manta. Safely reachable from about October to April. ^{6, 2}

One operator puts a sharper number on the dry-season dip. From May to October reef mantas enter their reproduction period and spread out, and central-site counts fall to about 1 to 5 animals a dive, against 10 to 20 at a single station in January and February. ⁶ October is the turn in that curve: counts build from there through December.

The academic record backs the direction of travel. A study of 1,085 individually identified reef mantas in the park, covering 2013 to 2018, recorded more animals moving from the southern site to the central sites than the other way, and logged its highest single-day count of foraging mantas at Karang Makassar during the northwest monsoon of November to April. ⁸

When does Komodo's rainy season start?

The park sits in one of Indonesia's driest corners. October is the hinge, and 2026 arrived at its dry season on schedule.

Komodo's dry season runs May to October, on 800 to 1,000mm of rain a year and daytime air around 40°C. ¹¹ Indonesia's meteorological agency dated the 2026 dry season to April, May and June, beginning in Nusa Tenggara, the region Flores and Komodo sit in, after a weak La Niña ended in February. ¹²

The ground held to that on the research date. BMKG's live page for Labuan Bajo read 26°C air, clear skies, 83% humidity and a light 3 km/h easterly at 18:00 WITA on 26 September 2026, with clear to partly cloudy conditions and 23 to 30°C forecast through 5 October. ¹³

October is where the calendar turns, and the published rainfall figures for Labuan Bajo argue with each other about how hard. One long-term dataset puts the month at 89mm across about four rainy days. A second gives 99mm, then contradicts itself further down the same page with 146mm across twelve days, a spread of 57mm between the low and high figures. ²

The practical read, from the operator that raised the rainfall problem in the first place: the first half of October generally behaves like September, dry and bright and steady, and the second half starts hinting at what is coming. ² Book the first fortnight if the weather matters more than the mantas.

How do you plan a trip that reaches both halves?

Five decisions, in the order they bind. The window comes before the boat, and the boat comes before everything else.

Only a liveaboard of five to six nights or more reaches both zones on one trip, and only in the transitional windows of roughly March to April and September to October. In peak dry season the south is typically rough, and no day trip out of Labuan Bajo gets there at all. The one-week Komodo itinerary walks through what that boat and that route look like. ^{1, 2}

1. 01

   Pick the window before you pick the boat

   September and October for the seam, or March and April for the other one. For the south alone, October to April, with December to February the strongest stretch for Manta Alley. ^{1, 2}

2. 02

   Count the nights, not the days

   The southern sites are liveaboard-only and Manta Alley sits 4 to 5 hours from Labuan Bajo harbour. Five to six nights is the floor for a route that works both halves. ^{2, 1}

3. 03

   Book three to six months out

   The park's 1,000-visitor-a-day quota in 2026 has tightened the booking window for July through October, by one operator's account. ⁵

4. 04

   Pack two suits

   A 3mm or shorty for the north, a 5mm with a hood for the south, on the same boat in the same week. Confirm the operator's rental sizes before you leave the thicker one at home. ^{1, 2}

5. 05

   Ask which zones the itinerary actually covers

   Operators drop Manta Alley from the route when the swell is up. Some years it settles in the first week of October, some years not until November, so ask which zones the itinerary actually covers. ²

Certification sets the rest. The central cleaning stations and Siaba Besar are Open Water work; Castle Rock, Crystal Rock and Manta Alley want an Advanced card and current experience. ^{6, 3} Komodo sits inside a wider Indonesian trip for most people, and the Indonesia country guide covers the islands and the arrival.