American Samoa Weather: Forecasts, Climate & Best Time to Visit

By Erika Müller · Data: National Park Service · ← Complete guide American Samoa

National Park of American Samoa is the only U.S. national park in the Southern Hemisphere, between the equator and the Tropic of Capricorn in the middle of the Pacific. Temperatures never really drop, and rain never quite stops. The short answer is that two seasons shape the year. The wet season runs from October through May, with heavy rain and a risk of cyclones. The dry season lasts from June through September, with shorter showers and much more favorable conditions for visiting. That's the window we recommend. Our complete guide to National Park of American Samoa covers everything you need to plan your trip.

14-Day Forecast

In a tropical climate, forecasts beyond seven days are less reliable than they are in temperate regions. Weather models struggle to predict the exact path of convective showers. Treat three- or four-day forecasts as reliable guidance. Beyond that, use them as a general trend.

Month-by-Month Climate in National Park of American Samoa

The figures below reflect climate normals for Pago Pago on Tutuila, the main island and the location of the visitor center. Temperatures change very little from month to month. Rainfall is what really makes the difference.

The annual temperature range is remarkably narrow. Only 2 to 4°F separate the coolest month from the warmest. Along the coast, low-lying areas of Tutuila receive an average of 125 inches of rain per year. The exposed ridges and summits of the interior mountains can get more than 299 inches. For comparison, Paris receives about 25 inches annually.

Don't picture constant rain. Tropical showers are often brief and intense. You might get ten minutes of torrential rain, followed by sunshine. During the wet season, longer spells lasting several hours or sometimes an entire day are common. In the dry season, showers tend to be brief and predictable.

Climate by Season

Dry Season (June–September)

This is the season we favor for most hikes and dives. Rainy days become much less common, showers don't last as long, and the risk of cyclones is almost zero. Nighttime lows drop by 2 to 4°F, making physical exertion on the trails more comfortable.

Tutuila's trails are less muddy, trips to the islands of Taʻu and Ofu are more reliable, and underwater visibility improves around the coral reefs. Our hiking guide covers conditions on each trail.

Wet Season (October–May)

Rainfall picks up sharply in October. Between November and April, tropical depressions can form in the South Pacific and develop into serious cyclones. The NPS temporarily closes certain areas of the park when a warning is in effect, especially exposed trails and high-elevation access routes.

The heat feels heavier because humidity never really lets up. The scenery remains striking in the rain. The jungle turns an almost unreal shade of green, and waterfalls swell. The park stays lightly visited year-round anyway, but during the wet season, build some flexibility into your itinerary.

Does It Get Cold in American Samoa?

No, it doesn't get cold in American Samoa. The thermometer almost never drops below 72°F, even at night during the dry season. The total annual range is barely 5 to 7°F, making this one of the most stable climate systems in the entire national park system.

What can feel cool is the wind on Tutuila's ridges or during boat trips to the outlying islands, not the air temperature. On the water, a windbreaker makes all the difference.

On the other hand, don't underestimate the heat. With relative humidity regularly above 85%, 84°F can feel much hotter. Hiking is considerably more demanding than it is in a dry mountain environment, so plan to carry twice as much water as you would in a mainland park.

What to Wear by Season

During the dry season (June–September): Wear lightweight, breathable fabrics such as linen, technical cotton, and quick-drying synthetics. Bring a light windbreaker for boat trips and high-elevation hikes. Lightweight trail shoes or closed-toe sandals work well. Trails stay damp even outside the rainy season. Trekking poles help on muddy stretches of forest trail.

During the wet season (October–May): Bring reliable rain gear, such as a full-coverage poncho or Gore-Tex jacket, and keep it in your pack at all times. Pack several spare T-shirts. Soaked cotton becomes uncomfortable quickly in 85% humidity. For hikes, waterproof or quick-drying shoes are essential. Keep camera gear, your passport, and medications in dry bags, even inside your backpack.

Year-round: UV levels are high all year because of the park's position near the equator. SPF 50+ sunscreen, a hat, and sunglasses are essential. Bring effective insect repellent. Mosquitoes are active at dawn and dusk, especially along the forest edge.

Alerts and Conditions to Watch

Tropical cyclones: The South Pacific cyclone season runs from October through April, with a peak between December and March. The National Weather Service operates an office in Pago Pago that issues regular bulletins. Before setting out on an isolated trail such as Vatia, Afono, or Mount ʻAlava, or planning a trip to Taʻu or Ofu, check the forecast for the next 48 hours. A cyclone can form and intensify in less than 24 hours at these latitudes, so don't leave without checking.

Flash floods: Intense rain can cause sudden flooding in valleys and along coastal trails. If a stream is visibly running higher than it was when you started, turn around immediately. Never attempt to cross a flooded stream on foot, even if the water looks shallow. Tropical currents are deceptive.

Roads and land access: Landslides can temporarily block the roads connecting park villages such as Vatia, Fagasa, and Afono after heavy rain. Check with the Pago Pago visitor center before taking mountain roads after an intense rainstorm. The NPS may temporarily close areas for safety reasons or trail repairs.

Access to the outlying islands: Trips to Taʻu and Ofu-Olosega take place by air, usually by charter, or by sea. Local flights may be canceled or delayed without notice in bad weather. Always leave extra room in your schedule, especially during the wet season.

Frequently Asked Questions