In Guam, the climate is tropical, hot and humid all year round. Guam is an island administered by the United States and located in the western Pacific Ocean between the Equator and the Tropic of Cancer; geographically, it is part of Micronesia.
Temperatures are very stable, and are around 30/32 °C (86/90 °F) during the day and 24/25 °C (75/77 °F) at night, all year round. Here are the average temperatures in Tamuning.
Tamuning - Average temperatures
Min (°C)242424252525252525252525
Max (°C)303030313131313131313030
Min (°F)757575777777777777777777
Max (°F)868686888888888888888686

The rainfall is abundant, above 2,000 millimeters (80 inches) per year; the rainiest period is from July to November, while the driest one is from January to April, when, however, there is still a moderate amount of showers and thunderstorms. Here is the average precipitation.
Tamuning - Average precipitation

The amount of sunshine in Guam is not excellent, though it is acceptable or good from January to June; from July to December, during the wettest period, it is quite scarce. Here are the average sunshine hours per day.
Tamuning - Sunshine


Guam's sea is warm enough to swim in all year round, as can be seen in the following table.
Guam - Sea temperature
Temp (°C)282828282929292929292928
Temp (°F)828282828484848484848482

Tropical cyclones

The island lies in the path of typhoons, the tropical cyclones of Southeast Asia and the Philippine Sea. Typhoons can cause more or less serious damage, bringing heavy rains and strong winds, and normally occur from May to December, though they are more frequent from August to November. Sometimes, however, they have affected the island outside of this period, as happened with typhoon Roy (in January 1988), Isa (in April 1997), and Kong-rey (not strong, in April 2007).

Best Time

The best time to travel to Guam is from February to April, since it is the least rainy period of the year, and (normally) outside of the typhoon season.

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, and a light raincoat or umbrella.
When going to the reef, you can bring snorkeling equipment, including water shoes or rubber-soled shoes.