Vanuatu's long stretch of islands means the climate varies considerably between the tropical north (over 4000mm/157in of rainfall a year) and the subtropical south. But whenever you come you're pretty much guaranteed pleasant weather. From January to July the average high drops from 28°C (83°F) to 24°C (76°F), likewise lows move from 23°C (73°F) to 19°C (67°F). Rainfall is mostly brief and abundant but can be prolonged for a day or so in the wetter months, between November and April.
The prevailing winds throughout the year are from the southeast (the famous Southeast Trade Winds of sailing ship days), bringing sunny days and cool nights. However, in the wet season the winds are more variable. Squalls can blow up in a few minutes, reaching 90km/h (56mi/h)and presenting a real danger to any small sailing vessels. In fact, any vessel caught in the open sea is in grave danger. Otherwise, just get a close-fitting hat. If you've booked a bungalow and it blows away, not to worry; your host will build another, pronto. They're used to cyclones.