Guide · Seasons
The honest answer is: whichever month suits you. The useful answer is what actually changes between the dry and the wet season — and it's less than you'd think.
The short version
The reefs around Gili Air are diveable all year. The sites sit at depths and in a topography that the weather doesn't reach very far into, so a wet-season dive is a different dive rather than a worse one. The water temperature barely moves across the year, and every site is a five to fifteen minute boat ride away, so a choppy morning costs you a few minutes of comfort rather than a day of diving.
What does change is the visibility, how busy the island is, and what turns up out in the blue. You'll notice we describe this by season rather than handing you a month-by-month table. That's deliberate — the seasons here shift from year to year, and a table that claimed to know what the third week of February looks like would be making it up.
April to October
This is the season people picture. Calm seas, long flat days, and the best visibility of the year — commonly 25 to 35 metres. On a site like Simon's Reef or Deep Turbo that's the difference between seeing the shape of the whole thing and seeing the bit in front of your mask.
The water is at its warmest from May through August. If you want those conditions without the company, September and October are the sweet spot, with May and June close behind: the sea has settled, the visibility is up, and the island hasn't filled yet.
July and August are the busiest weeks of the year on Gili Air. The diving is still excellent, but boats are fuller, accommodation books out, and courses need arranging further ahead. If those are your dates, message us early. We cap groups at four divers per guide and we won't stretch that to fit more people in.
November to March
Wet season here doesn't mean weeks of rain. It means heavier, shorter showers, often overnight or in a burst in the afternoon, and more plankton in the water. Visibility comes down to something like 10 to 25 metres — less glassy, greener, with the light arriving differently.
That plankton is also why some divers come deliberately in these months. It's food, and food draws bigger animals in. Manta sightings are more likely now than in the dry season. Likely is not the same as expected, and we come back to that below.
The water sits one or two degrees cooler than in high summer, which in practice means nothing at all: you're still in 27-degree water in a 3 mm suit. The island is quieter, and you'll often have a site to yourselves.
How it feels
Most of our dives are drift dives. Rather than fighting a current, we let it carry us along the reef while the boat follows the bubbles and picks us up wherever we surface. It's a relaxed way to dive, and it's why divers who've only ever done anchored dives often say their first Gili dive felt effortless.
Currents around Gili Air are usually gentle. A handful of sites can run medium to strong — Gili Air Wall, Shark Point, Deep Turbo, Halik, Meno Wall and Simon's Reef among them — and those we keep for divers with the experience to enjoy them. That's a judgement made on the morning, about the group and the water, not something written into a calendar.
Because every site is only five to fifteen minutes away, we can also change plan on the day. If one site is running hard, we go and dive another one instead.
What lives here
Green and hawksbill turtles are the constant. They're on very nearly every dive here — Gili Air's reputation as a turtle island is earned, and our house reef is called Turtle Point for a reason.
Alongside them, all year: white-tip and black-tip reef sharks, which are small, shy and completely harmless and are seen at Shark Point almost daily; blue-spotted stingrays; cuttlefish and octopus; moray eels; bumphead parrotfish; schooling jacks and trevally; sweetlips, groupers, angelfish and clownfish.
If you like small things, this is a very good place to be. Frogfish, ghost pipefish, seahorses and pygmy seahorses, nudibranchs, harlequin shrimp and garden eels are all here, and mandarin fish come out at dusk. Sites like Hans Reef reward the divers who move slowly and look twice.
Mantas, whale sharks and mola mola do turn up around the Gilis. All three are chance encounters rather than residents, and no month guarantees them. Manta sightings are more likely in the wet season, roughly December to March; whale sharks and mola mola are genuinely rare.
We mention them because you'll read about them elsewhere and it's fair that you know where they stand. If big pelagics are the whole reason for your trip, plan that trip somewhere they actually live, and treat a Gili sighting as the bonus it is.
Choosing
Four common reasons for a trip, and the months that suit each one.
September or October, with May and June close behind. Calm water, visibility at the top of its range, and the island not yet full.
Any month. The sites we use for courses are shallow, sheltered and gentle, the water is warm enough that nobody gets cold in a pool session, and conditions vary far less here than the seasons suggest.
The wet season, November to March. Lower visibility, more plankton, fewer people, and a real chance of something big drifting past.
Come anyway — the diving is excellent. Just book earlier than you would otherwise, because the island is at its busiest and we hold our groups to four divers per guide.
One practical note
Because the sites are minutes rather than hours away, a morning here is comfortably two dives with a surface interval back at the centre in between, and you still have the afternoon. That changes how you plan a short trip: three full days on Gili Air is a real amount of diving, not a token amount.
It also means a bad weather morning rarely writes off a day. We can wait an hour, or swap to a more sheltered site, and still get in the water.
Yes. The dry season from April to October brings the calmest seas and the best visibility, and the wet season from November to March still dives well — the depth and topography of these sites mean the weather doesn't affect them as much as you'd expect.
The water sits at 27 to 30 °C all year, around 28 to 29 °C most of the time, warmest between May and August and about one to two degrees cooler from December to March. Deeper sites can drop to around 24 °C. A 3 mm shorty or full wetsuit is all you need, and it's included.
Across the year it runs between roughly 10 and 35 metres. In the dry season, May to October, expect around 25 to 35 metres. In the wet season, November to March, plankton brings it down to roughly 10 to 25 metres — and brings bigger animals in with it.
For conditions, the dry season from April to October, with September and October the sweet spot and May and June close behind. July and August are the busiest weeks. The wet season from November to March is quieter, with lower visibility and a better chance of mantas.
Maybe. Mantas are a chance encounter around the Gilis, not residents, and sightings are more likely in the wet season roughly from December to March. Whale sharks and mola mola are rarer still. We'd rather tell you that than sell you a sighting nobody can promise.
Almost certainly. Green and hawksbill turtles are on very nearly every dive here, and our house reef is a turtle site.
Usually gentle. Most of our dives are relaxed drift dives, with the boat following your bubbles. A few sites can run medium to strong and are kept for more experienced divers, and which sites we dive on a given morning depends on the group and the water that day.
Ready when you are
Send us your dates and we'll tell you honestly what the diving is likely to be like — and what needs booking ahead.
