Map from Google - Tuvalu

Tuvalu, Oceanian archipelago located south of the equator, has an equatorial climate, ie hot, humid and rainy throughout the year. The rains, occurring in the form of downpours of thunderstorms, do not last long and do not greatly reduce the hours of sunshine.
The temperatures are very stable throughout the year, around 77 °F at night, and 88 °F during the day. The trade winds blow throughout the year, but especially during the period from April to October, tempering a little the heat.
Here are the average temperatures of the capital Funafuti.
Average temperatures - Funafuti
Min (°F)777777777777777777777777
Max (°F)888888888888888888888888

Precipitation is definitely abundant, since it exceeds 120 inches per year.
In the capital Funafuti, 125 in of rain per year fall, with a peak between December and March, when they are equal to or greater than 12 inches per month, and a minimum (very relative...) between May and October, when they drop below 10 inches per month. Here is the average precipitation.
Average precipitation - Funafuti
Prec. (in)14.212.412.

In the northernmost islands, the rainfall is slightly less abundant.
Tuvalu are affected by the tropical cyclones of the Southern Hemisphere, in the period November to mid-May (although sometimes they have occurred outside of this period, as happened with Bebe on late October 1972, and Keli in June 1997). Being not far from the equator, the islands are generally affected by cyclones at the beginning of their formation, but considering that Tuvalu is one of the flattest countries in the world, cyclones can cause flooding, but also storm surges, even if they are not are very strong or if they pass at a certain distance. The northernmost islands (Nanumea, Niutao, Nanumanga), closer to the equator, are located at the edge of the area, where cyclones are rare.


For swimming, the sea is warm all year round, as we can see in the following table.
Sea temperature - Funafuti
Sea (°F)848484868684848484848686

When to go

The best time to travel to Tuvalu is from mid-May to late October, being a relatively less rainy period, and out of the cyclone season. Since sometimes there have been cyclones outside of the canonical period, to go on the safe side, you can choose the period from July to mid-October.

What to pack

All year round, tropics-friendly, loose fitting clothing, sun hat, a scarf for the breeze, a light sweatshirt for the evening, light raincoat or umbrella.