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Umatac surfForecast / Guam / Guam
12 Day Weather and Surf, issued 9 am Thursday 18 Sep 2025 ChST
Best Forecast Surf Conditions for Umatac this week:
The surf forecast for Umatac over the next 12 days: The first swell (rated 1 star or higher) is forecast to arrive on Monday (Sep 22) at 1AM. The primary swell is predicted to be 0.6m and 9s period. The wind is predicted to be offshore as the swell arrives.
The most powerful waves expected at Umatac in the next 12 days are 0.9m 11s and forecast to arrive on Thursday (Sep 25) at 7AM. Winds are predicted to be cross-shore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.1m 7s period and expected on Monday (Sep 22) at 10PM.
| Wave Type | Time (ChST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 1AM (Mon 22nd Sep) | 2ft (0.6m) 9s |
| Best Surf | 1AM (Mon 22nd Sep) | 2ft (0.6m) 9s |
| Most Powerful | 7AM (Thu 25th Sep) | 3ft (0.9m) 11s |
Table - best surf conditions forecast for Umatac over the next 12 days.
Short Range Forecast Heavy rain (total 27mm), heaviest during Sat night. Warm (max 29°C on Sat afternoon, min 27°C on Thu night). Wind will be generally light. | Days 3-6 Weather Summary Heavy rain (total 28mm), heaviest during Mon night. Warm (max 28°C on Sun morning, min 27°C on Sun morning). Wind will be generally light. | ||||||||||||||||||||
Thursday 18 | Friday 19 | Saturday 20 | Sunday 21 | Monday 22 | Tuesday 23 | Wednesday 24 | |||||||||||||||
| AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | |
Rating (10 max) | |||||||||||||||||||||
Swell Height Map |  |  |  |  |  |  |  | ||||||||||||||
| Wave Height (m) & direction (?) | |||||||||||||||||||||
| Period(s) (?) | 5 | 10 | 11 | 8 | 3 | 9 | 10 | 9 | 9 | 9 | 8 | 9 | 9 | 9 | 8 | 10 | 10 | 11 | 10 | 10 | 11 |
Wave (?)Graph  | |||||||||||||||||||||
 kJ (?) | 0 | 0 | 0 | 0 | 9 | 0 | 7 | 6 | 15 | 25 | 35 | 60 | 76 | 73 | 49 | 37 | 98 | 150 | 106 | 55 | 167 |
Wind (km/h) | |||||||||||||||||||||
| Wind State (?) onshore cross-onshore cross-shore cross-offshore offshore glassy | cross- off | cross- off | off | cross | cross | cross- off | cross- off | cross- off | cross- off | off | off | off | cross- off | off | cross | cross- off | cross- off | cross- off | cross- off | cross | cross |
High Tide / height (m) | 6:39PM 0.72 | 5:06AM 0.65 | 7:09PM 0.72 | 6:07AM 0.67 | 7:35PM 0.72 | 6:59AM 0.68 | 7:57PM 0.71 | 7:47AM 0.68 | 8:16PM 0.69 | 8:31AM 0.68 | 8:34PM 0.69 | 9:15AM 0.66 | 8:51PM 0.67 | ||||||||
Low Tide / height (m) | 11:16AM -0.04 | 12:08AM 0.42 | 12:07PM -0.02 | 12:47AM 0.35 | 12:50PM 0.02 | 1:22AM 0.28 | 1:28PM 0.07 | 1:54AM 0.22 | 2:01PM 0.13 | 2:25AM 0.17 | 2:32PM 0.20 | 2:54AM 0.12 | 3:01PM 0.27 | 3:24AM 0.10 | |||||||
Thursday 18 | Friday 19 | Saturday 20 | Sunday 21 | Monday 22 | Tuesday 23 | Wednesday 24 | |||||||||||||||
| Sunrise | 6:09 | - | - | 6:09 | - | - | 6:09 | - | - | 6:09 | - | - | 6:09 | - | - | 6:09 | - | - | 6:09 | - | - |
| Sunset | - | 6:21 | - | - | 6:20 | - | - | 6:19 | - | - | 6:17 | - | - | 6:17 | - | - | 6:16 | - | - | 6:15 | - |
 | |  |  | | | | |  | | |  | | | | | | | |  | | |
Rain (mm) | - | - | 5 | 3 | 1 | 3 | 4 | 2 | 9 | - | - | - | - | 2 | 8 | 5 | 6 | 7 | 7 | 8 | 2 |
| Temp. °C | 28 | 28 | 28 | 28 | 28 | 28 | 28 | 29 | 28 | 28 | 27 | 27 | 28 | 27 | 27 | 28 | 28 | 28 | 28 | 27 | 28 |
| Feels °C (?) | 32 | 29 | 28 | 30 | 28 | 28 | 29 | 32 | 30 | 29 | 28 | 28 | 30 | 30 | 29 | 30 | 31 | 30 | 29 | 27 | 30 |
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Recent Eyeball Surf Reports for Guam
Previously calm conditions have become cross-shore at Umatac (light winds from the NNE at SHIP27 13 km from Umatac). 0.3m 7s swell from the NNW to make surfable waves.
1 h 29 min ago
FREE! Surf-Forecast.com widget for your website
The surf report / weather widget below is available to embed on third party websites free of charge and provides a summary of our Umatac surf forecast. Simply grab the html code snippet that we provide and paste it into your own site. You can choose your preferred language and metric/imperial units for the surf forecast feed to suit users of your site. Click here to get the code.
Information about the Umatac Surf forecast
The above surf forecast table for Umatac provides essential information for determining whether the surfing conditions will be good over the next 12 days. A general guide to surfing at Umatac can be found by selecting the local surf guide option on the grey menu. Our Umatac surf forecast is unique since it includes wave energy (power) that defines the real feel of the surf rather than just the height or the period. If you surf the same spot (Umatac) regularly then make a mental note of the wave energy from the surf forecast table each time you go. Very soon you may start to choose your surf days based on the wave energy alone combined with our forecast of favourable offshore wind conditions. Our star ratings will help here and of course you will also find the usual wave height and period predictions on our surf forecasts as well as a full break down of the swell components under our advanced users option (to reveal that, click the little Einstein character under the tide times).
Further information to help with frequently asked questions about our surf forecast for Umatac may be found under the help tab on the top menu and also by moving your mouse over the question marks on the surf forecast table itself. Please always bear in mind that the forecast is for near-shore open water and local factors at each surf break influence the actual breaking wave height, such as the beach / reef profile, water depths offshore and shelter.
Umatac is 22 km (14 miles) from Agana. If you plan a holiday in Guam, look for hotels and other accommodation in Agana. Agana has rooms for a wide range of budgets as well as car hire and transport links.
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