Het weer in Rarotonga (Cook Islands) in september

September is the turn towards Rarotonga's warmer half - longer days, temperatures picking up - and the forum's phrase for it is dry but breezy, with the equinox winds arriving as usual around the middle of the month. That makes the accommodation decision for you: stay sheltered from the south-easterly, which means the western side of the island, because the south and east take the full run of it and a cold wind there makes for a poor week. The other September draw is the humpbacks, whose season runs July to October, with Black Rock the spot people name on Rarotonga itself. The record: 24.5C days, 18.2C nights, 10.1 precipitation days carrying 83mm, 9.9 hours of sun, a 23.9C sea and a 30.7 kph wind.

Regulars are specific this counts as the coldest month of the year here on paper, though conditions can still run genuinely warm and pleasant with no particular cold snap in a given year, part of the broader April-to-November dry, cooler season. Our row backs that mild, genuinely wet and windy read, 23.9C over 17.7C nights feeling 15C, with a substantial 104.1mm of rain across 10.2 days and a real 30.5 kph wind. Regulars are consistent which side of the island you're on matters a lot, the northeast staying meaningfully more sheltered while Muri and the east/southeast catch the colder trade wind directly. This also counts as a good month for whale watching along the corridor from Avarua harbour to the Edgewater. The sea sits at a cooler but still swimmable 25C. The record: 9 hours of sun and AQI 42.

The rainy season here runs November to April, and regulars are clear that April is its tail end - much less rain than January or February, most of what does fall arriving overnight, with short refreshing showers by day and plenty of fine ones between them. The trade winds mean the island splits in two on any given afternoon: one side gets the shower, the other stays in the sun. Our row shows the easing rather than an arrival - 27.2C over 21C, humidity beginning to drop from its wet-season peak, with 136.5mm across 16.3 days and a 27.6C lagoon. No cyclone risk left to speak of by this point in the season. The record: 9.5 hours of sun, a 29.2 kph wind and AQI 39.

June is winter here and regulars treat that as a real thing rather than a joke: cool days, chilly nights, and warm clothing needed after dark, while still being mild next to New Zealand. Their figures are our row to the degree - mid-to-high 70s by day and mid-60s at night against our 24.8C over 18.5C. The sea can feel cold, though the lagoon at low tide in sun is comfortable once you are moving. Two details make the month concrete: the prevailing south-easterly blows hard enough to make the Muri and Titikaveka stretch the chilly side of the island, and the sun sets around six, so the evenings are long and cool. The record: 73.4mm across 9.6 days, 8.8 hours of sun, a 30.8 kph wind and a 25.3C sea.

October ends the Rarotongan dry season and residents call it unpredictable in the fullest sense: you might get a week of rain or a week of clear sun. Our row's 115.9mm across 9.2 days is about thirteen millimetres a wet day, so when it comes it means it. Days warm to 24.7C. The detail they always add is the nights, which drop below 20C - ours is 18.6C reading as 17C - so pack one long-sleeved jumper even for a tropical island. The south-easterly trades keep running and the spring wind picks up from mid-September, which our 31.8 kph average confirms; the lagoon has not warmed up yet at 24.2C. In exchange it is shoulder season and quiet. The record: humidity 75 percent, 10 hours of sun and AQI 47.