Surf Forecasts:
Aha Rivermouth surf forecast from 13 Sep 2026:
- Best quality surf: Sunday 20 Sep, 12PM (local time) - 10ft (3.0m), 15s period, E swell with cross-shore winds.
- Most powerful swell: Sunday 20 Sep, 6AM (local time) - 10ft (3.0m), 16s period, E swell with 4,161 kJ wave energy.
- Next surfable swell (1★+): Sunday 20 Sep, 12PM (local time) - 10ft (3.0m), 15s period with E swell.
Best Forecast Surf Conditions for Aha Rivermouth this week:
The surf forecast for Aha Rivermouth over the next 16 days: The first swell (rated 1 star or higher) is forecast to arrive on Sunday (Sep 20) at 12PM. The primary swell is predicted to be 3.0m and 15s period with a secondary swell of 1.6m and 8s. The wind is predicted to be cross-shore as the swell arrives.
The most powerful waves expected at Aha Rivermouth in the next 16 days are 3.0m 16s and forecast to arrive on Sunday (Sep 20) at 6AM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.3m 8s period and expected on Saturday (Sep 19) at 12PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 12PM (Sun 20th Sep) | 10ft (3.0m) 15s |
| Best Surf | 12PM (Sun 20th Sep) | 10ft (3.0m) 15s |
| Most Powerful | 6AM (Sun 20th Sep) | 10ft (3.0m) 16s |
Table - best surf conditions forecast for Aha Rivermouth over the next 16 days.
The Lowdown
Hey, Rusty here. Let’s talk about what Aha Rivermouth is doing over the next couple of weeks.
To be straight with you, it’s a rough start. We’ve got a solid run of poor conditions through the first week. Winds are onshore or cross-onshore almost every day, and the swell is small and short-period. Water temp is about 84° – nothing unusual for the time of year.
The first real bright spot doesn’t show up until Sunday, September 27th. That morning we’ll see light offshore winds from the SSE with clean surf. Swell is 4ft from the east with an 11-second period. Energy is moderate at 439. It’s not huge, but the wind makes it the cleanest session of the whole forecast. That’s the one to aim for. Monday the 28th morning offers a little more size at 5ft from the east with a longer 12-second period and energy up to 905, but the wind turns onshore again, so it’ll be choppier.
If you’re looking at the bigger stuff on the 19th and 20th of September – waves up to 10ft from the east with very long 17-second periods and energy over 4000 – those are all blown out by strong cross-onshore winds. That’s kite-surfing territory, not for the paddle crew.
So, don’t hold your breath for the first couple of weeks. Sunday the 27th is your best bet.
Rusty.
Short Range ForecastModerate rain (total 10mm), heaviest on Tue night. Warm (max 28°C on Sun afternoon, min 27°C on Sun night). Wind will be generally light. | Days 5-7 Weather SummaryLight rain (total 5mm), mostly falling on Wed night. Warm (max 28°C on Wed afternoon, min 27°C on Wed night). Wind will be generally light. | |||||||||||||||||||
Sun 13 | Monday 14 | Tuesday 15 | Wednesday 16 | Thursday 17 | Friday 18 | Saturday 19 | ||||||||||||||
PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | |
Swell Height Map |  |  |  |  |  |  |  | |||||||||||||
Wave Height (m) Direction Period (s) | E 7 | E 8 | E 8 | E 9 | E 9 | E 9 | E 10 | E 10 | E 10 | E 10 | ENE 14 | E 9 | ENE 13 | ENE 13 | E 9 | ENE 12 | E 19 | E 17 | E 17 | E 16 |
Wave Graph  | ||||||||||||||||||||
 kJ | 131 | 153 | 177 | 181 | 181 | 207 | 266 | 223 | 188 | 148 | 160 | 139 | 135 | 133 | 83 | 82 | 354 | 1485 | 2652 | 3664 |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | on | cross-on | cross-on | cross-on | cross-on | cross-on | on | cross-on | on | on | cross-on | cross-on | on | on | on | cross-on | on | cross-on | cross-on | cross-on |
High Tide | 7:53PM2.07m | 8:19AM1.99m | 8:18PM2.05m | 8:53AM1.87m | 8:43PM1.99m | 9:28AM1.73m | 9:07PM1.91m | 10:07AM1.57m | 9:31PM1.81m | 10:57AM1.42m | 9:55PM1.68m | 12:42PM1.31m | 10:25PM1.55m | |||||||
Low Tide | 2:09AM0.35m | 2:16PM0.58m | 2:41AM0.37m | 2:41PM0.71m | 3:14AM0.43m | 3:04PM0.85m | 3:49AM0.52m | 3:26PM0.99m | 4:30AM0.64m | 3:44PM1.14m | 5:28AM0.75m | 3:51PM1.27m | ||||||||
 |  |  |  |  |  | | | | |  | | | | | | | | | | |
 | — | — | 6:11 | — | — | 6:11 | — | — | 6:11 | — | — | 6:11 | — | — | 6:13 | — | — | 6:13 | — | — |
 | 6:34 | — | — | 6:32 | — | — | 6:31 | — | — | 6:30 | — | — | 6:30 | — | — | 6:28 | — | — | 6:27 | — |
mm | 3 | 2 | — | — | — | — | — | 5 | — | — | 1 | 1 | — | 3 | — | — | — | — | — | 1 |
Temp °C | 28 | 28 | 28 | 28 | 28 | 28 | 28 | 27 | 28 | 28 | 28 | 28 | 28 | 28 | 27 | 27 | 27 | 28 | 28 | 27 |
Feels °C | 29 | 30 | 30 | 30 | 30 | 31 | 31 | 30 | 31 | 30 | 30 | 31 | 31 | 31 | 30 | 28 | 28 | 29 | 28 | 26 |
Swell 1 Height (m) Direction Period (s) | E 14 | E 13 | E 8 | E 9 | E 9 | E 9 | E 10 | E 10 | E 10 | E 10 | E 9 | E 9 | E 9 | E 9 | E 9 | E 9 | E 19 | E 17 | E 17 | E 16 |
| kJ | 101 | 130 | 177 | 181 | 181 | 207 | 266 | 223 | 188 | 148 | 139 | 139 | 104 | 97 | 73 | 52 | 354 | 1485 | 2652 | 3664 |
Swell 2 Height (m) Direction Period (s) | N 6 | N 5 | E 13 | E 13 | E 13 | E 12 | NNW 6 | NNW 6 | NNW 6 | NNW 7 | ENE 14 | ENE 13 | ENE 13 | ENE 13 | ENE 12 | ENE 12 | E 8 | E 11 | E 10 | — |
| kJ | 6 | 5 | 89 | 87 | 87 | 77 | 11 | 13 | 27 | 46 | 160 | 137 | 135 | 133 | 83 | 82 | 49 | 123 | 68 | — |
Swell 3 Height (m) Direction Period (s) | S 6 | S 6 | N 5 | N 5 | — | NNW 6 | ENE 16 | ENE 15 | E 14 | ENE 14 | NNW 7 | NNW 7 | N 6 | N 7 | N 7 | N 6 | ENE 12 | S 8 | S 8 | — |
| kJ | 3 | 3 | 4 | 2 | — | 7 | 48 | 23 | 97 | 145 | 35 | 17 | 20 | 35 | 23 | 13 | 81 | 11 | 11 | — |
Wind waves Height (m) Direction Period (s) | E 7 | E 8 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | N 4 | N 4 | N 4 | N 5 |
| kJ | 131 | 153 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 10 | 20 | 28 | 73 |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 70 | 44 | 44 | 12 | 40 | 12 | 40 | 12 | 12 | 40 | 12 | 12 | 40 | 12 | 66 | 595 | 595 | 595 | 595 | 595 |
Best forecast wave conditions in Okinawa | ||||||||||||||||||||
Best forecast wave conditions in Japan | ||||||||||||||||||||
Header Global | ||||||||||||||||||||
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Information about the Aha Rivermouth Surf forecast
The above surf forecast table for Aha Rivermouth provides essential information for determining whether the surfing conditions will be good over the next 16 days. A general guide to surfing at Aha Rivermouth can be found by selecting the local surf guide option on the grey menu. Our Aha Rivermouth 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 (Aha Rivermouth) 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 Aha Rivermouth 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.
Aha Rivermouth is 31 km (19 miles) from the city of Okinawa. If you plan a holiday in Okinawa, look for hotels and other accommodation in Okinawa. Okinawa has rooms for a wide range of budgets as well as car hire and transport links.
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