Sea temperature in Guam
Live water temperatures and swimming conditions across 2 beaches on the Guam coast.
Best time to swim in Guam
The sea in Guam peaks in July, when the water averages around 23°C.
The main swimming season runs from January – December, when surface temperatures stay comfortable for extended sessions.
On average, 12 months a year sit above 20°C — the threshold most swimmers describe as pleasant without a wetsuit.
The coldest month is typically January at around 20°C, when cold-water swimmers dominate the coast.
Guam sea temperature history
Long-term climatology for Guam shows an annual mean sea temperature of 21°C, ranging from 20°C in winter to 23°C at the summer peak.
The seasonal swing is roughly 3°C between the coldest and warmest month — a useful yardstick when comparing years or checking whether the current sea is running above or below average.
Recent decades have trended slightly warmer at Guam, in line with regional sea-surface temperature records for the wider basin.
Monthly averages below are drawn from multi-decadal climatology and are updated as new observations arrive.
Values are area averages; individual beaches vary by exposure and depth.
Guam sea temperature: frequently asked questions
What is the warmest month to swim in Guam?
July is the warmest month in Guam, when the sea averages about 23°C. Late-season warmth often persists a few weeks after peak.
When is the sea coldest in Guam?
The coldest month in Guam is typically January, when the water averages around 20°C. Cold-water swimmers and surfers dominate this period.
When can you swim in Guam without a wetsuit?
The main swimming season in Guam runs from January – December — about 12 months a year when the sea sits above 20°C, the level most swimmers describe as pleasant without a wetsuit.
Do I need a wetsuit in Guam?
Outside peak summer the water in Guam drops toward 20°C, so a 3/2mm shorty or full wetsuit makes long swims much more comfortable. In peak months most swimmers go without.
What is the average sea temperature in Guam?
The long-term annual mean sea temperature in Guam is about 21°C, based on multi-decadal climatology of the surrounding waters.
How do I check the current sea temperature in Guam?
The live reading at the top of this page shows the current sea temperature in Guam, updated hourly from marine buoy and satellite data. The 7-day forecast covers water, air, waves, wind and UV for the week ahead.
Guam sea temperature by month
Average sea temperatures around Guam for every month of the year, based on long-term Open-Meteo marine climatology.
| Month | Average sea | Swimming comfort |
|---|---|---|
| January | 20.0°C | Swimmable, refreshing |
| February | 20.0°C | Swimmable, refreshing |
| March | 20.0°C | Swimmable, refreshing |
| April | 20.0°C | Swimmable, refreshing |
| May | 21.0°C | Pleasant swimming |
| June | 22.0°C | Pleasant swimming |
| July ⭐ | 23.0°C | Pleasant swimming |
| August | 23.0°C | Pleasant swimming |
| September | 23.0°C | Pleasant swimming |
| October | 22.0°C | Pleasant swimming |
| November | 21.0°C | Pleasant swimming |
| December | 20.0°C | Swimmable, refreshing |
Monthly figures are modelled climatology averages, not live readings. How accurate is our data?
Warmest beaches in Guam right now
| Beach | Region | Sea | Swim score |
|---|---|---|---|
| Ritidian Beach | Yigo | 23.6°C | Excellent |
| Tumon Beach | Tumon | 23.2°C | Excellent |
Sea temperature in Guam — FAQ
How warm is the sea in Guam in September?
The sea off Guam averages about 23.0°C in September, based on long-term monthly averages for this coast.
When is the best time to swim in Guam?
Guam is warmest in July (around 23.0°C) and coldest in January (around 20.0°C). There are typically 5 months a year when the water sits above 22°C.
What is the average yearly sea temperature in Guam?
Across all twelve months, the sea in Guam averages about 21.3°C.
Do you need a wetsuit to swim in Guam?
In peak season (around July, ~23.0°C) most swimmers are comfortable without a wetsuit. Outside summer, when the water drops toward 20.0°C, a 3/2mm to 5/4mm wetsuit is recommended.