The most important thing in advance: The Maldives can be visited all year round as the climate is subtropical. With air temperatures averaging 30 degrees and water temperatures of 27-28 degrees, you can have a dream vacation in the Maldives at any time.
However, the best time to travel is the dry season, which lasts from November to April. At this time there are about 9 hours of sunshine a day. Short showers may occur. The period between November and April is considered the peak season. A vacation is most expensive at this time.

The southwest monsoon, i.e. the rainy season, prevails between May and October. During this time there may be intense rainfall and strong winds. However, a holiday in the Maldives is significantly cheaper at this time. May to October is low season.

Here is a figure that best describes the climate and rainfall in the Maldives:

In general, it should be mentioned that the duration and intensity of the rainy or dry season varies from year to year. From my own experience I can say that in the last two years there has been a relatively large amount of rain in December, but the dry season has extended into May.
In my experience, the optimal weather for sun worshipers is from January to March. Temperatures can rise to 32 degrees and there is relatively little wind. Rain is extremely rare at this time.

The best time for diving & snorkeling

The best travel time for divers and snorkelers is between January and April. At this time the visibility underwater is great and the sea is calm. The underwater world shows its most beautiful side with various animals and plants. But the rainy season can be pretty charming, as the chance to encounter Manta Rays and Whale Sharks is higher.

The Unterwaterworld of the Maldives 

During the rainy season the sea is stormier. However, there are also plenty of reasons to go diving and snorkeling at this time. Manta Ray season is between May and November and manta rays can be observed from very close distances. However, with a bit of luck you can also be spotted outside of the season.

The chances of spotting whale sharks also increase during the rainy season. A particularly large number of Whale Sharks can be spotted in the northern Baa Atoll. During the dry season, the greatest chance of seeing Whale Sharks is in South Ari Atoll.

The best time for surfing

The southwest monsoon period between May and October is particularly windy. What is a disadvantage for bathers and sun worshipers, all surfers get their money’s worth, because the wind is great for windsurfing and kitesurfing.

Surfing in the northern atolls of the capital Malé is best done between April and October. In the southern atolls, surfing conditions are best between February and November.