Map from Google - Vanuatu
In Vanuatu the climate is influenced by the trade winds, and it's equatorial
in the northern islands, ie hot and rainy all year round, while it's tropical
in the central and southern islands, ie hot and rainy from December to March, and cool with less rainfall from May to October.
The islands are in fact scattered over an axis, oriented from north to south, about 900 kilometres long; the southernmost islands are located at a latitude of 20 degrees south.
Many of the islands are volcanic, and have inland slopes which enhance precipitation
. The rains are most abundant in the northernmost islands, where even 4,000 millimetres of rain per year fall (see Vanua Lava), including 200 mm per month even in the least rainy months (which are July and August), and more than 450 mm in March (the rainiest). Proceeding south, the rains decrease gradually, down to 2,200/2,500 mm in the southern islands, even though in the small and flat islands they go down to 1,500 mm.
The period from December to March
is hot, humid and rainy across the country, with highs around 29/31 °C and lows around 23/25 °C. The rains come in the form of intense downpours, which soon leave room for the sun.
The winter season, from July to September
, is warm in the northern islands, with highs around 27/28 °C, as we can see from the average temperatures of Vanua Lava.
Average temperatures - Vanua Lava
The rains in Vanua Lava, as in general in the northern islands having an equatorial climate, are abundant throughout the year. Here the average rainfall.
Average precipitation - Vanua Lava
In these northern islands, the sea
is warm all year round, as we can see in the following table.
Sea temperature - Vanua Lava
Moving south, winter becomes gradually cooler; in the capital Port Vila
, in the central island of Shefa, the daytime temperature is around 25/26 °C, while in the southern islands it drops to 23/24 °C. At night the average temperature is around 21/22 °C in the northern islands, and around 17/18 °C in the central and southern islands, where it can sometimes even drop to 13/15 °C.
Average temperatures - Port Vila
In Port Vila, as in general in the central and southern islands, the decrease in rainfall from May to October is evident. Here is the average rainfall.
Average precipitation - Port Vila
For swimming, the sea
remains quite warm even in the central islands, where the sea temperature drops to 26 °C from June to October.
Sea temperature - Port Vila
In the southernmost islands, the temperature becomes even cooler, so that from July to September, the average daily temperature drops to 20 °C, as we can see from the data of Aneityum.
Average temperatures - Aneityum
Consequently, in the southernmost islands even the sea becomes cooler, and from July to October the water temperature drops to 24 °C, so it's still warm enough for swimming, as we can see from the data of Aneityum.
Sea temperature - Aneityum
The amount of sunshine
in Vanuatu is never great, but it's neither poor: the sun is never missing, but some cloudiness, maybe associated with showers and thunderstorms, is always possible. In Port Vila, even in the least rainy months, from July to October, there are about 12 days with showers and thunderstorms per month.
The Vanuatus are affected by tropical cyclones
from November to mid-May, but they are most likely from December to April. Outside of this period, there has been Cyclone Xavier which passed near the northern islands on late October 2006.
When to go
The best time
to visit Vanuatu is from July to September in the northern islands (up to Sanma and Malampa), because it is less hot and rainy; while in the central and southern islands which include the capital, the best time is from May to October. Since from June to September in the central and southern islands it can get cool, you may prefer the period mid-May to mid-June and even more October, when it's a bit warmer and the heavier rains are still to come. Even in the least rainy months, however, there are plenty of showers, especially in the northernmost islands.
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 for the southern islands; light raincoat or umbrella. For the reef, equipment for snorkeling, water shoes or rubber soled shoes.
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.