In Flores, an Indonesian island belonging to the group of the Eastern Lesser Sunda Islands (Nusa Tenggara), and in the nearby Alor Archipelago, the climate is tropical, hot all year round, with a muggy and rainy season from December to March, and a dry season from June to September. In the rainy season, the sun shines for a few hours a day, in fact it usually rains a couple of hours in the morning and a couple of hours in the afternoon.
Temperatures are high and quite uniform throughout the year. The least hot period is from June to August. From September to November, and sometimes from mid-August, the hottest period of the year occurs, when the temperature can reach 35/37 °C (95/99 °F), especially on the north side. In the rainy season, on the other hand, high humidity makes the heat muggy.
Here are the average temperatures of the most important city, Maumere, located on the northern coast.
Maumere - Average temperatures
Min (°C)252424242423232223242525
Max (°C)313131323231313132333432
Min (°F)777575757573737273757777
Max (°F)888888909088888890919390

Throughout the year, 1,600 millimeters (62 inches) of rain fall, with a maximum from December to March and a minimum from June to September. Here is the average precipitation in Maumere.
Maumere - Average precipitation

In Flores, there's plenty of sunshine in the dry season, while in the rainy season the sun shines for a few hours a day, between one rain shower and another. In the interior of the island, a blanket of clouds often lies over the mountain peaks.
Maumere - Sunshine

As mentioned, in the interior there are hills and mountains; the highest peak is Poco Mandasawu, 2,370 meters (9,350 feet) high, located in the western part of the island, while in the eastern part we find Kelimutu volcano, 1,639 meters (5,377 ft) high, and characterized by the presence of three lakes that change color. If you are planning some hiking at high altitudes, keep in mind that above 1,000 meters (3,300 feet) it's cool in the evening and at night, especially in the dry season, while above 2,000 meters (6,500 feet) it can get quite cold.
Here are the average temperatures of Ruteng, located at 1,100 meters (3,600 feet) above sea level, on the northern slope of Poco Mandasawu.
Ruteng - Average temperatures
Min (°C)171716161514131314151617
Max (°C)242425252525252526262625
Min (°F)636361615957555557596163
Max (°F)757577777777777779797977

In the mountainous areas, the rains are definitely more abundant: in Ruteng they amount to 3.575 mm (140 in) per year. During the dry season it does not rain much, but sometimes some thunderstorms occur, more often than on the coast.
Ruteng - Average precipitation

In 2003, in the cave of Liang Bua, north of Ruteng, the fossil remains of hominids lived up to 50,000 years ago have been discovered.

Lakes of Kelimutu volcano

The sea in Flores is warm enough to swim in throughout the year: the water temperature ranges from 27 °C (81 °F) in July and August, to 29 °C (84 °F) between November and May.
Flores - Sea temperature
Temp (°C)292929292928272728293029
Temp (°F)848484848482818182848684

From November to mid-May, but more often from January to mid-April, Flores can be affected by tropical cyclones, which are formed on the sea of Timor, and then move south-westard, between the Sunda Islands and Australia.

Best Time

The best time to travel to Flores and enjoy its beaches, is from June to August: the sun shines, the heat is not too intense, and in any case, it's tempered by the breeze; there are just some short downpours or thunderstorms every now and then. In September, the rains have not started yet, but it starts to get very hot at low altitude. In late September or in October, the rains often increase in inland and mountainous areas.

What to pack

All year round, bring light clothes of natural fibers, a sun hat, a scarf for the breeze, a light sweatshirt for the evening. From December to March, a light raincoat or umbrella.
When going to the reef, you can bring snorkeling equipment, including water shoes or rubber-soled shoes.
When going mountain climbing, bring hiking shoes, a sweatshirt or sweater, a jacket, and a raincoat.