Surf Forecasts:
Aha Rivermouth surf forecast from 13 Sep 2026:
- Most powerful swell: Sunday 20 Sep, 12PM (local time) - 10ft (3.0m), 14s period, E swell with 3,813 kJ wave energy.
Best Forecast Surf Conditions for Aha Rivermouth this week:
The most powerful waves expected at Aha Rivermouth in the next 16 days are 3.0m 14s and forecast to arrive on Sunday (Sep 20) at 12PM. 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 3PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | - | - |
| Best Surf | - | - |
| Most Powerful | 12PM (Sun 20th Sep) | 10ft (3.0m) 14s |
Table - best surf conditions forecast for Aha Rivermouth over the next 16 days.
The Lowdown
Alright, Rusty here. Let's chew the fat on what Aha Rivermouth has cookin' over the next couple of weeks.
Truth is, it's a bummer of a stretch. We've got a 16-day window, but there's a big fat gap at the start. From Monday the 14th all the way through Friday the 18th, the surf is weak and mean. Waves are tiny—anywhere from about 2 ft to 4 ft—but the wind is garbage; cross, onshore, or cross-onshore, just messin' up the surface. The combined wave energy is low, between 266 and 154. Not worth paddlin' out.
Now, come Saturday the 19th, things get a bit crazy. A proper long-period groundswell pushes in from the east, showing 5 ft to 10 ft waves with periods hitting 16 seconds. That’s a heap of energy—the combined swell readings fly up to 1223 on Saturday morning and peak at 3904 by Sunday afternoon. That's some serious power. But here's the rub: the wind cranks up from a moderate to a strong cross-onshore, then turns into a cross-shore gale from the north and northwest. With that kind of wind on a beach/jetty spot like this, it’s going to be a washing machine. Those big, long-period waves will be closing out and blown to bits. Honestly, this setup is screaming for kite surfers, not paddle surfers. For the experts, the size blows past 8 ft on the 20th and 21st, but the quality is just poor—strong cross-chop and lumpy.
After that peak, the swell drops off, but the wind doesn't give in. From the 22nd through the 29th, we're stuck with onshore and cross-onshore winds from the north and northeast. Wave heights bounce between 2 ft and 8 ft, but the combined energy is moderate at best (a few days around 715 to 1041, then fadin'). It’s all choppy and messy. There's no standout session anywhere in this forecast. The big days are blown out, and the smaller days are just flat and windy.
So, the long and short of it: there ain't a single good surfable day in this entire 16-day run. If you're desperate, maybe that mid-week after the 22nd could give you a rough, bumpy ride, but you'd be better off takin' a break. Forecasts can turn, but for now, it's a total washout.
- Rusty
Short Range ForecastModerate rain (total 14mm), heaviest on Sun night. Warm (max 28°C on Sun night, min 26°C on Mon morning). Wind will be generally light. | Days 5-7 Weather SummaryLight rain (total 7mm), mostly falling on Wed night. Warm (max 28°C on Wed night, min 27°C on Wed night). Winds increasing (light winds from the E on Thu morning, fresh winds from the NNE by Sat afternoon). | ||||||||||||||||||
Monday 14 | Tuesday 15 | Wednesday 16 | Thursday 17 | Friday 18 | Saturday 19 | ||||||||||||||
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 8 | E 8 | E 9 | E 9 | E 9 | E 10 | E 10 | E 10 | E 10 | E 9 | E 9 | ENE 13 | ENE 13 | E 9 | ENE 12 | E 19 | E 16 | E 16 | E 16 |
Wave Graph  | |||||||||||||||||||
 kJ | 153 | 177 | 177 | 185 | 207 | 266 | 228 | 184 | 148 | 171 | 139 | 135 | 133 | 83 | 82 | 171 | 996 | 2434 | 3245 |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | cross | on | cross-on | on | cross-on | cross-on | on | on | cross-on | cross-on | on | on | on | on | on | cross-on | cross-on | cross-on |
High Tide | 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 | 5 | 1 | — | 3 | 2 | 1 | 1 | 1 | — | 1 | 2 | — | — | 1 | 1 | 2 | — | — | — |
Temp °C | 28 | 27 | 28 | 27 | 28 | 28 | 27 | 28 | 28 | 28 | 28 | 28 | 28 | 28 | 28 | 28 | 28 | 28 | 28 |
Feels °C | 31 | 28 | 30 | 28 | 31 | 31 | 30 | 31 | 31 | 30 | 32 | 31 | 31 | 31 | 30 | 30 | 29 | 28 | 27 |
Swell 1 Height (m) Direction Period (s) | E 8 | 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 8 | E 8 | E 16 | E 16 | E 16 |
| kJ | 153 | 177 | 177 | 185 | 207 | 266 | 228 | 184 | 148 | 171 | 139 | 106 | 99 | 73 | 51 | 48 | 996 | 2434 | 3245 |
Swell 2 Height (m) Direction Period (s) | E 13 | E 13 | E 13 | E 13 | E 12 | NNW 6 | NNW 6 | NNW 6 | NNW 7 | ENE 14 | ENE 13 | ENE 13 | N 7 | ENE 12 | ENE 12 | E 19 | ENE 11 | S 8 | S 8 |
| kJ | 130 | 89 | 87 | 87 | 77 | 11 | 13 | 26 | 47 | 160 | 137 | 135 | 36 | 83 | 82 | 171 | 198 | 12 | 5 |
Swell 3 Height (m) Direction Period (s) | N 6 | N 5 | N 5 | NNW 5 | NNW 6 | ENE 16 | ENE 15 | E 14 | ENE 14 | NNW 7 | NNW 6 | N 6 | ENE 13 | N 7 | S 8 | ENE 12 | S 8 | S 8 | — |
| kJ | 5 | 4 | 2 | 5 | 7 | 48 | 23 | 97 | 105 | 41 | 23 | 20 | 133 | 23 | 22 | 81 | 12 | 12 | — |
Wind waves Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | — | — | — | — | — | N 6 | N 9 | N 8 | N 4 | N 5 |
| kJ | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 21 | 85 | 29 | 29 | 94 |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 44 | 12 | 12 | 40 | 40 | 12 | 12 | 40 | 40 | 12 | 12 | 40 | 40 | 66 | 70 | 40 | 595 | 595 | 595 |
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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