Været i Raja Ampat (Waisai) i september

This is one of the few months the board tells people not to book. September here is rough sea, strong currents and poor visibility in a windy, stormy stretch that runs to the end of the month or into early October, and the liveaboards simply stop running it - if the dive operators have written the month off, that is the clearest verdict available. Light snorkelling near shore still works if the trip is really a beach one, but they say to leave Wayag and Pianemo for another time. October, and then December through May, is where they send people. Our row explains it: 305.3mm across 24.5 precipitation days under 28.3C reading as 34C. The record: humidity 83 percent, a 29.8C sea and AQI 21.

Regulars quote local dive operators naming October as the actual best month here, this month landing within a window some call the dry season though real, frequent showers and thunderstorms remain a normal tropical feature regardless of that label. Our row backs that hot, genuinely wet read, 28.9C reading as a scorching 35C, over 25.9C nights feeling 31C, with a substantial 370.1mm of rain across 28 days and humidity at 84 percent. Regulars are consistent southeast winds can pick up and create rougher seas for boat trips during the broader window this falls within, worth checking conditions before a dive or island-hopping day. The remoteness and light air quality remain a real draw regardless of any single day's weather. The sea sits at a bath-warm 30.3C. The record: 9.7 hours of sun, a 10.2 kph wind and AQI 18.

Regulars describe this as near the tail end of the wet season, with sunny days common overall despite the calendar, and rain typically arriving as a roughly two-hour afternoon or evening shower every few days rather than sustained all-day rain. Our row shows a wetter reality than that framing implies, a striking 314mm of rain across 27 days - nearly every day - alongside warm, humid conditions, 28.8C reading as a hot 35C at 82.3 percent humidity, over 25.9C nights. This month also sits inside peak manta season, prized by regulars for reliable big-animal sightings even though the same nutrient-rich water that draws the mantas can reduce underwater visibility compared with the drier months later in the year. The sea holds a very warm 30.1C. The record: 9.4 hours of sun, an 11.5 kph wind and one of the cleanest air readings in this project, AQI 20.

Our row for November is the wettest in this entire collection - 289.2mm across 26.5 precipitation days - and divers who have been say it made no difference. The showers roll through in a couple of hours, a wet afternoon becomes a clear starry night, and one regular reports two weeks in the rainy season without a single dive postponed: calm sea, perfect visibility. October to April is the season they name, and November sits inside it. What the numbers do carry is the air: 28.8C over a 26.1C night at 83 percent humidity reads as 35C by day and 31C after dark, the muggiest row here, with barely any wind at 11.1 kph. The compensations are a 30.3C sea and AQI 16, the warmest water and the cleanest air anywhere in this dataset. The record: 10 hours of sun.

February sits in Raja Ampat's good run - October and December through May, depending which regular you ask - and the forum draws a distinction our rain figure cannot. There is rain here most days, but in February it falls mainly over the big islands rather than out on the water, so the diving is largely unaffected: visibility around 15 to 20 metres and currents not at their strongest. That matters because the alternative is July and August, when wind and rain are heavy enough that resorts have traditionally closed and the liveaboards gone elsewhere. Our own row reads properly wet, and honestly so: 24.2 precipitation days carrying 237.3mm. The rest: 28.8C days that feel like 35C, 26.1C nights, 9.5 hours of sun, a 29.7C sea and AQI 21.