Port Douglas (Great Barrier Reef) weather in September

September in Port Douglas sits just ahead of the two things that define the rest of the year here. Stinger season officially runs November to May, and although some nets go in earlier - late September in certain years - this is still the tail of the clear window, and the reef operators supply stinger suits regardless, so the outer reef is fine either way. The other absence is the wet: this is just before the rain and the real humidity settle in. The water is around 25C and warming, which is why August and September are the pair the forum names for reef trips. The record: 29.2C days that feel like 31C, 21.7C nights, 7 precipitation days carrying 40.8mm, 10.8 hours of sun and a 24.3C sea.

Regulars are specific this marks the beginning of the wet season here, though early in the month real rain stays relatively uncommon even as the heat and humidity crank up hard, the pattern genuinely hit or miss rather than a settled daily soak. Our row backs that hot, genuinely wet read, 33C reading as a scorching 37C, over 24.3C nights feeling 27C, with 61.7mm of rain across 6.7 days and humidity at 79 percent. Regulars are consistent this also marks the start of stinger season, a full-body suit required for anyone swimming in the ocean regardless of how warm the water looks, with genuinely heavy rain and cyclone risk still concentrated later, from around January through March. The sea sits at a bath-warm 28C. The record: 11.8 hours of sun, a 15.6 kph wind and AQI 34.

Regulars are specific that this sits outside stinger season, with the enclosure net typically removed from the start of this month through to November since the water runs too cool for them - a genuine safety upside of the cooler winter sea. Our row backs the mild winter read, 26C over 20.5C nights feeling 22C, with 58.9mm of rain across 7.7 days. Regulars also flag school holidays landing in this window and a real chance of wind picking up, both worth knowing since a windier day can disrupt reef trips even when the temperature itself stays comfortable. The sea sits at 24.1C. The record: humidity 84 percent, 9.8 hours of sun, a 16.3 kph wind and AQI 39.

June is the hinge of the stinger year rather than a settled side of it. The nets come out somewhere around the start of the month and stay out until about the start of November, because the water has cooled past what stingers want - but regulars are careful that the date moves by up to a fortnight depending on the water temperature and what the lifesavers' testing finds. Anyone arriving in early June should ask them at the northern end of the beach rather than trust the calendar. June is also picked over July for avoiding school holidays and the windier weather that comes with them. Our row gives 26.1C over 21.3C, 48.4mm across 8 precipitation days and a 24.5C sea. The record: humidity 85 percent, 9.6 hours of sun and AQI 37.

August sits at the end of the dry season regulars name - May to August, warm and not particularly wet, our row giving 42.5mm across 6.3 precipitation days under 27.2C. The reason they insist on it has nothing to do with rain. Stinger nets go in around the start of November and come out around the start of June, shifting a little with the water temperature, so in August there are no box jellyfish or irukandji to plan around: people swim a hundred metres either side of the flags and the sea is usually flat, at worst chopped by wind. On temperature they disagree among themselves - locals find 20 to 22C too cool for a relaxed swim while northern visitors call it perfect; our row says 23C. The record: 20.5C nights, humidity 82 percent, 10.2 hours of sun and AQI 40.