Map from Google - New_Caledonia

In New Caledonia, the climate is tropical, influenced by the trade winds, with a hot and rainy season, a cool and drier season, and two intermediate periods.
- The hot season, humid and rainy, runs from late December to late March. During this season the temperatures are high, around 30/32 °C during the day, but with peaks of 35 °C. The humidity makes the heat muggy, and rains in the form of showers and thunderstorms are frequent. The rains are more abundant in inland slopes of the main island, but also on the north-eastern coast of the island itself, where it exceeds 300 millimetres in the wettest month (March), while on the west coast they range from 200 mm in the north, to 150 mm in the south (see Nouméa). In this period, it is also possible that the islands are hit by tropical cyclones (see below). However, even in this period, between the heavy showers, the sun shines.
- A cool season, sunny and with little rains, from June to August or September, during which the daytime temperature drops on average to 23/24 °C, and the minimum around 17/18 °C, but sometimes it can drop a bit below, in fact sometimes highs drop to around 20 °C. In addition, there can be some cold-air outbreaks, which may lower the night temperatures to around 10 °C and even below, although in recent years they have become rare. Some showers are possible even in this period, most likely along the northern coast of the main island, where the proximity to the slopes enhances the formation of thunderclouds (see Poindimié).
- Two intermediate seasons, April-May and October-November, in which the temperature are acceptable, around 26/27 °C during the day, while rainfall is acceptable in the second period, and a bit higher in the first one, especially in April and in the rainiest areas.
Here are the average temperatures of Nouméa.
Average temperatures - Nouméa
Min (°C)232323222019171718192122
Max (°C)292929272624232324262729

The sea temperature is always warm enough for swimming, although it drops to 23 °C from July to October; in the northernmost islands (Belep Islands) it is just higher (about one degree Celsius).
Sea temperature - Nouméa
Sea (°C)262727262524232323232526

As mentioned, the main island has some mountain slopes, in fact it is crossed by a mountain range, whose highest peaks are Mont Panié, 1,629 metres high, and Mont Humboldt, 1,618 metres high.

The annual precipitation amounts to around 1,500/1,800 mm in the smaller islands, as you can be seen in the following table, concerning the rainfall in the island of Lifou.
Average precipitation - Lifou
Prec. (mm)195245320250130120110707080701501815

In the main island (Grande Terre), rainfall varies with slope exposure and proximity to the mountains: in general, the northern coast is rainier than the southern: in Poindimié, 2,600 mm of rain per year fall, with a minimum of about 90 mm in August and September; in Pouebo 1,900 mm fall, while on the southern coast, from 800 to 1,200 mm fall, therefore some areas are almost dry. In the capital Nouméa, in the south-west, 1,050 mm of rain per year fall, with a maximum of 150 mm in March, and a minimum of 45/50 mm per month from September to November. However, from year to year in New Caledonia the rains are quite irregular and therefore a bit unpredictable.
Here is the average precipitation in Nouméa.
Average precipitation - Nouméa
Prec. (mm)115125150105851157065405060801060

New Caledonia can be affected by tropical cyclones from November to mid-May, although they are more likely from December to April. Some intense cyclones that hit New Caledonia were Coleen in February 1969, Anne in January 1988, Sose in April 2001, Beni in January 2003, Erica in March 2003, Jasmine in February 2012, Evan in December 2012.

In addition, New Caledonia is affected by the climate cycle called ENSO. During the years of El Niño, in New Caledonia the weather tends to be drier than normal from December to February, and drier and cooler than normal from June to August. On the other hand, during the years of La Niña, it becomes more rainy than usual from December to February, and warmer from June to August.

New Caledonia

When to go

The best time to visit New Caledonia is the austral spring, ie October-November: the temperature is pleasant, the sun shines, the rains are generally not excessive, especially in the southern side of the main island and in the smaller islands. In the southern side of the main island, the rains are acceptable even in April and May, however, in April there's still some chance of cyclones or tropical storms, but this happens also in November (even though they are statistically rare). So, all in all the best month is probably October. From June to September, the weather can be nice, but sometimes it can be a little cool for beach life, especially for those who are sensitive to cold: you can then opt for excursions.

What to pack

In winter (June to August): light clothes for the day, a scarf for the breeze, a sweatshirt for the evening, possibly a light jacket; light raincoat or umbrella. For the reef, equipment for snorkeling, water shoes or rubber soled shoes. For Mont Panié, hiking boots, sweatshirt, raincoat.
In summer (December to February): tropics-friendly, loose fitting clothing, sun hat, a scarf for the breeze, a light sweatshirt for the evening, light raincoat or umbrella.