Guam — Sea Water Temperature and Annual Ranges
Up-to-date sea water temperatures for the coasts of Guam. Learn about today’s conditions, monthly averages, and how the surrounding seas and oceans vary by season. We find every place where you can swim and show you the water temperature there today and throughout the year.
Sea Water Temperature Along the Coast
Chart of Average Temperature Changes Over the Last 60 Days
Places with the Warmest Sea Water Today
The Most Popular Seaside Places
Coastal Seas and Oceans
Water Temperature and Swimming Overview
Regions and Map
Water Temperature Trends
Guam’s coastal waters are characteristically warm year-round, making the island a popular destination for swimming, snorkeling and diving. Sea surface temperatures typically range from about 26°C to 30°C (79°F to 86°F). The coolest period is usually in late winter to early spring, roughly February and March, when readings hover near 26°C (79°F). The warmest months tend to be late summer into early autumn, around August through October, when temperatures commonly reach 29–30°C (84–86°F). Because the island sits in the western Pacific tropics, these variations are relatively small and the water generally feels pleasantly warm without the need for wetsuits for most swimmers.
Swimming Conditions
Swimming is widely permitted across Guam’s beaches, and many shorelines and bays offer calm conditions suitable for casual swimmers, especially on the sheltered leeward side where coral reefs provide natural protection. However, seasonal weather patterns such as the rainy and typhoon seasons (roughly June–December) can produce stronger winds, higher surf and rip currents, particularly on exposed, windward coasts. Marine hazards including sharp coral, sea urchins and occasional jellyfish can occur, so it’s advisable to choose lifeguarded beaches, observe local warning flags and follow advice from authorities or dive operators. Overall, the warm, clear waters of Guam support year-round swimming and a wide range of water activities, with local conditions determining day-to-day safety and comfort.