Surf Forecasts:
Aha Rivermouth surf forecast from 8 Sep 2026:
- Best quality surf: Friday 11 Sep, 3AM (local time) - 4ft (1.2m), 9s period, N swell with cross-offshore winds.
- Most powerful swell: Thursday 10 Sep, 3PM (local time) - 5ft (1.5m), 10s period, N swell with 422 kJ wave energy.
- Next surfable swell (1★+): Friday 11 Sep, 3AM (local time) - 4ft (1.2m), 9s period with N 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 Friday (Sep 11) at 3AM. The primary swell is predicted to be 1.2m and 9s period with a secondary swell of 0.5m and 9s. The wind is predicted to be cross-offshore as the swell arrives.
The most powerful waves expected at Aha Rivermouth in the next 16 days are 1.5m 10s and forecast to arrive on Thursday (Sep 10) at 3PM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.6m 7s period and expected on Sunday (Sep 13) at 6AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 3AM (Fri 11th Sep) | 4ft (1.2m) 9s |
| Best Surf | 3AM (Fri 11th Sep) | 4ft (1.2m) 9s |
| Most Powerful | 3PM (Thu 10th Sep) | 5ft (1.5m) 10s |
Table - best surf conditions forecast for Aha Rivermouth over the next 16 days.
The Lowdown
Alright, Rusty here. Let’s have a look at what’s on the cards for Aha Rivermouth over the next couple of weeks.
Right off the bat, it’s a bit of a tough start. We’ve got a long stretch of poor conditions ahead. The first week is looking pretty grim, with onshore and cross-shore winds making a mess of the 5ft to 6ft swell that rolls in early on. The water temp is sitting right on average for this time of year at 83°, so at least it’s warm, but the wind is a killer. The combined energy is moderate early on, around 536 (moderate wave energy), but the quality is just not there. For the first several days, I wouldn't bother paddling out.
We do see a bit of a lull mid-week with tiny, poor surf, and then things get worse again with strong, messy winds. There’s a real blank run here from the 8th all the way through to the 15th of September with nothing worth recommending.
Things finally start to look up on Tuesday the 15th. The afternoon turns clean with a light cross-offshore wind and a 4ft swell from the east, period at 10 seconds – that’s proper groundswell. The combined energy is still moderate at 273. This is a real turning point. We get a good run of surf right through to Thursday the 17th. The best of it looks to be on Wednesday the 16th of September, with glassy conditions in the afternoon and a clean 3ft east swell. The energy sits around 249. This is the standout period, with clean, fun waves on offer. Thursday the 17th also holds nice glassy morning conditions with a clean 3ft swell. This is where you want to be.
After that, it starts to taper off again. Friday the 18th is marginal, and by the weekend we are back to small, onshore junk with tiny swell for the rest of the forecast. The combined energy drops below 100 (weak wave energy) by the 20th, so it’s pretty much done.
So, the call is clear: the best surf is on Wednesday the 16th and Thursday the 17th of September. Get in the water then. The rest of the window is a write-off for paddle surfing, and with those strong onshore winds later on, that river mouth setup might look better for the kite crew than us surfers.
Rusty.
Short Range ForecastLight rain (total 5mm), mostly falling on Fri morning. Warm (max 28°C on Thu afternoon, min 26°C on Wed night). Winds decreasing (fresh winds from the NNW on Tue afternoon, light winds from the E by Thu night). | Days 5-7 Weather SummaryModerate rain (total 10mm), heaviest on Sun afternoon. Warm (max 28°C on Fri afternoon, min 27°C on Fri night). Wind will be generally light. | |||||||||||||||||||
Tue 8 | Wednesday 9 | Thursday 10 | Friday 11 | Saturday 12 | Sunday 13 | Monday 14 | ||||||||||||||
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) | NNW 9 | NNW 8 | N 8 | N 8 | N 8 | N 9 | N 10 | N 9 | N 9 | N 8 | ENE 14 | SE 6 | E 14 | E 14 | E 14 | E 14 | E 8 | E 8 | E 9 | E 9 |
Wave Graph  | ||||||||||||||||||||
 kJ | 488 | 238 | 251 | 264 | 257 | 380 | 422 | 246 | 151 | 84 | 64 | 88 | 103 | 103 | 97 | 101 | 133 | 160 | 153 | 194 |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross | cross-on | cross-on | cross-on | cross-on | on | cross-on | cross-on | cross | cross | cross | cross | cross-on | cross-on | on | on | on | cross-on | on | cross-on |
High Tide | 5:38PM1.80m | 5:01AM1.91m | 6:08PM1.90m | 5:49AM2.03m | 6:36PM1.98m | 6:31AM2.10m | 7:02PM2.03m | 7:09AM2.12m | 7:28PM2.07m | 7:44AM2.08m | 7:53PM2.07m | 8:19AM1.99m | 8:18PM2.05m | |||||||
Low Tide | 11:15PM0.94m | 11:40AM0.32m | 11:55PM0.76m | 12:17PM0.29m | 00:30AM0.59m | 12:51PM0.31m | 1:04AM0.46m | 1:22PM0.37m | 1:36AM0.38m | 1:50PM0.46m | 2:09AM0.35m | 2:16PM0.58m | 2:41AM0.37m | |||||||
 |  |  | | | | |  |  | | | | |  | | | | | | | |
 | — | — | 6:09 | — | — | 6:09 | — | — | 6:09 | — | — | 6:09 | — | — | 6:11 | — | — | 6:11 | — | — |
 | 6:39 | — | — | 6:38 | — | — | 6:37 | — | — | 6:36 | — | — | 6:35 | — | — | 6:34 | — | — | 6:32 | — |
mm | — | — | — | — | — | — | — | 3 | 2 | — | 2 | — | — | — | 1 | 4 | — | 3 | 2 | 1 |
Temp °C | 27 | 27 | 27 | 27 | 27 | 27 | 28 | 28 | 28 | 28 | 27 | 27 | 27 | 27 | 27 | 27 | 27 | 27 | 27 | 27 |
Feels °C | 26 | 27 | 27 | 27 | 28 | 31 | 32 | 33 | 31 | 30 | 29 | 29 | 29 | 29 | 28 | 28 | 28 | 29 | 29 | 29 |
Swell 1 Height (m) Direction Period (s) | NE 8 | ENE 8 | ENE 9 | E 9 | N 10 | N 9 | N 10 | N 9 | N 9 | N 8 | N 8 | N 7 | SE 6 | N 7 | S 7 | E 14 | E 13 | E 8 | E 9 | E 9 |
| kJ | 34 | 22 | 26 | 26 | 18 | 380 | 422 | 246 | 151 | 84 | 57 | 54 | 56 | 23 | 25 | 101 | 92 | 160 | 153 | 194 |
Swell 2 Height (m) Direction Period (s) | S 8 | S 8 | S 8 | S 8 | E 9 | E 9 | E 9 | E 9 | E 6 | ESE 6 | ENE 14 | ENE 14 | N 7 | E 14 | E 14 | S 7 | S 7 | E 13 | E 13 | N 5 |
| kJ | 20 | 11 | 10 | 10 | 15 | 42 | 40 | 40 | 22 | 18 | 64 | 66 | 38 | 103 | 97 | 17 | 9 | 89 | 87 | 11 |
Swell 3 Height (m) Direction Period (s) | E 9 | ESE 10 | ESE 10 | E 7 | SE 9 | S 7 | S 7 | ESE 7 | ESE 9 | ENE 15 | S 7 | E 9 | E 14 | ESE 10 | NNW 6 | ESE 9 | N 6 | S 7 | S 7 | ENE 13 |
| kJ | 14 | 10 | 10 | 4 | 21 | 8 | 8 | 9 | 15 | 43 | 4 | 6 | 103 | 18 | 13 | 26 | 6 | 9 | 4 | 58 |
Wind waves Height (m) Direction Period (s) | NNW 9 | NNW 8 | N 8 | N 8 | N 8 | — | — | — | — | — | SE 6 | SE 6 | — | SE 7 | E 5 | E 6 | E 8 | N 5 | NNE 4 | — |
| kJ | 488 | 238 | 251 | 264 | 257 | — | — | — | — | — | 37 | 88 | — | 86 | 35 | 56 | 133 | 4 | 9 | — |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 596 | 595 | 595 | 595 | 919 | 31 | 12 | 12 | 12 | 12 | 12 | 12 | 66 | 66 | 70 | 70 | 70 | 70 | 40 | 66 |
Best forecast wave conditions in Okinawa | ||||||||||||||||||||
Best forecast wave conditions in Japan | ||||||||||||||||||||
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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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