Bora Bora
weather.

01 · Two seasons

Two seasons,
one thermometer.

Météo-France Polynésie describes two seasons in the Society Islands: a warm, more humid one from November to April, and a cooler, less humid one from May to October, with December and January the wettest months². At Bora Bora the split is sharp in the rain gauge and soft on the thermometer.

December, the wettest month, averages 250.7 mm; July, the driest, 61.9 mm, a quarter as much¹. Mean highs run from 31.4 °C in March to 28.9 °C in July, and the nights barely move: the mean low stays between 23.9 and 25.8 °C all year¹. In the 1991–2020 normals the station never recorded a day with a high of 20 °C or less¹.

All of this comes from one station, 3 m above sea level on the airport motu¹. Météo-France notes that in the Society Islands the coasts exposed to the trade wind, and above all the heights, are much wetter², so the island's slopes, Otemanu's included, can be wetter than these airport figures. The motu resorts sit at the same low level as the station.

05 · Rain

How the rain
actually falls.

Monthly totals hide the pattern. December's 250.7 mm falls over 16.8 rain days, about 15 mm a rain day, and an average December has 1.1 days of 50 mm or more¹. Tahiti Tourisme describes wet-season showers as generally brief, followed by sun⁶; the numbers bear out the heavy-shower part.

The dry season is drier, not dry. July still has 9.4 days with rain, against 17.2 in January¹. What matters for a lagoon tour is how often a whole day is lost: 50 mm days happen about 5.5 times a year at the airport, and all but a fraction of them between October and May¹.

The extremes belong to the warm season: the wettest day on record, 435.5 mm on 24 November 1983, and 385.7 mm on 15 April 1987¹. Météo-France publishes no sunshine record for this station¹; Tahiti Tourisme's figure for the islands is 7 hours of sun a day from November to February and 8 from March to October⁶.

06 · Wind

The trade wind
and the mara'amu.

The wind follows the seasons the other way round from the rain. The 10-minute mean at the airport is 4.5 to 4.9 m/s (16–18 km/h) from December to April and 5.4 to 5.7 m/s (19–21 km/h) from June to October¹.

The strong south-east trade wind of the cool season has a name, the mara'amu. On the water it shows as chop across the open stretches of the lagoon, which matters more on a paddleboard or in a small boat than on a resort pontoon. With the year's lowest temperatures, it makes July and August the least sticky months.

Storm gusts are another matter. The station's records, kept since 1981, top out at 40 m/s (144 km/h), on 11 March 1983 and 25 April 1998; outside the November–April season the strongest gust is 30.4 m/s (109 km/h), on 31 August 2009¹. Météo-France treats wind as dangerous from a 65 km/h mean or 100 km/h gusts inland, thresholds that vary by region⁷.

07 · The sea

The sea,
27 to 29 °C.

The lagoon never gets cool. Monthly averages run from 26.9 °C in August and September to 29.1 °C in March and April, and the lowest monthly minimum in ten years of data is 25.9 °C, in July and September³. When we checked, these figures agreed within half a degree with WeatherSpark's⁸.

Most snorkelers swim without a wetsuit in any month; a rash vest is about sun and coral as much as warmth. The cool-season months bring the humpback whales: the environment directorate's leaflet puts them around the islands from July to the end of October, in winter water of 21 to 27 °C across the territory⁹.

09 · Cyclones

Cyclones:
rare, not hypothetical.

In the southern hemisphere the cyclone season runs from November to April, sometimes into May⁴. Destructive storms used to be rare in French Polynesia: national meteorological archives counted fourteen between 1831 and 1982¹².

Then came 1982–83, when six cyclones struck the territory in five months, in a season of unusually warm water that a French Senate report traced to a wider imbalance in the tropical Pacific¹². Since then the Leeward Islands, Bora Bora included, have been hit in 1997, 1998 and 2010¹³¹⁴⁵.

The airport's own record shows the pattern: its four strongest gusts all fell between December and April¹. Many seasons pass with no storm near the island. When one does come, Météo-France Polynésie runs the cyclone alert and its map at meteo.pf¹⁵.