Season by season
Dry season (December–June)
The best time for the loop: clearer skies, less mud on the trails and good visibility from the overlooks and Mount Lamlam. The hills turn golden-brown as the grass dries, and grass fires sometimes leave black patches. Trade winds blow onto the east coast, so expect surf at Talofofo and Ipan while the western bays stay calm.
Wet season (July–November)
The south is at its greenest and the waterfalls are at their fullest, but heavy showers can hide the views and turn the red clay of the hiking trails into a slide. Rivers rise fast, so leave river hikes for a settled spell and set off early — mornings are often dry even in the wettest months.
Sea conditions & typhoons
Most of the south has no protecting lagoon apart from Merizo, and swells reach the shore directly. The Inarajan pools are safe in calm weather but dangerous when waves wash over the rocks. Typhoons are possible in any month and likeliest from about August to November; after a storm, expect fallen branches and occasional road closures on the loop.
Month by month
| Month | Avg high | Avg low | Rainfall | Crowds |
|---|---|---|---|---|
| January | 30°C | 24°C | 130 mm | Busy |
| February | 30°C | 24°C | 110 mm | Busy |
| March | 30°C | 24°C | 70 mm | Quiet |
| April | 31°C | 25°C | 80 mm | Quiet |
| May | 31°C | 25°C | 110 mm | Quiet |
| June | 31°C | 25°C | 165 mm | Quiet |
| July | 31°C | 25°C | 300 mm | Busy |
| August | 31°C | 24°C | 410 mm | Busy |
| September | 31°C | 24°C | 360 mm | Quiet |
| October | 31°C | 24°C | 300 mm | Quiet |
| November | 31°C | 25°C | 210 mm | Quiet |
| December | 30°C | 24°C | 150 mm | Busy |
Temperatures and rainfall are approximate long-term averages; individual years vary, and a single typhoon can change a month completely.
Festivals & events
- March: Guam History and Chamorro Heritage Day, early in the month, centres on Umatac with a re-enactment of Magellan’s landing and village festivities (check the date and programme)
- March or April: on Good Friday pilgrims carry crosses up Mount Lamlam; the trail and roadside are very busy that morning
- July: around Liberation Day on 21 July, Merizo holds memorial services for the victims of the Tinta and Faha massacres — visitors are welcome if respectful
- Late spring: Agat has often held a mango festival when the fruit is in season (check whether it is running)
- All year: each village celebrates its patron saint with a fiesta weekend of church services and shared food; ask locally what is on
Our advice
Pick a clear weekday between January and May for the loop: the overlooks are at their best and the Inarajan pools are quiet. In the wet season, watch the forecast and be ready to swap days. Whenever you come, leave early — the south is at its loveliest before the midday haze. See when to go for the regional picture.
