Guam has a tropical marine climate. Fanumnangan(dry season) and fanuchanan(rainy season) are the two main seasons. The best time to embark on Guam tours is during the period of July through December. It is easier to move around and explore attractions when it is not raining all the time.
Guam basically has a warm and pleasant climate all year through. The mean annual temperature is 81 degrees.
The only thing about Guam is that it lies in the ‘Pacific Typhoon Alley’. The last time a dangerous typhoon hit Guam was way back in 2002. These typhoons tend to strike the region once in 8 or 10 years.
| Weather | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
| Average in Fahrenheit | 76 | 77 | 78 | 79 | 79 | 80 | 80 | 80 | 79 | 80 | 80 | 79 |
| Average in Centigrade | 24 | 25 | 26 | 26 | 26 | 27 | 27 | 27 | 26 | 27 | 27 | 26 |
| Rainfall in inches | 5.16 | 4.26 | 2.97 | 4.03 | 4.49 | 5.19 | 9.59 | 12.16 | 14.08 | 14.40 | 8.51 | 5.85 |
| Relative humidity % | 77 | 76 | 75 | 74 | 73 | 76 | 76 | 81 | 81 | 80 | 80 | 78 |
| Daily Sunshine Hours | 11.15 | 11.30 | 11.51 | 12.16 | 12.40 | 12.58 | 13.00 | 12.47 | 12.24 | 12.00 | 11.35 | 11.18 |
