Surf Forecasts:
Aha Rivermouth surf forecast from 13 Aug 2026:
- Most powerful swell: Tuesday 18 Aug, 3PM (local time) - 4ft (1.2m), 9s period, E swell with 241 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 1.2m 9s and forecast to arrive on Tuesday (Aug 18) 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 2.0m 9s period and expected on Friday (Aug 21) at 12AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | - | - |
| Best Surf | - | - |
| Most Powerful | 3PM (Tue 18th Aug) | 4ft (1.2m) 9s |
Table - best surf conditions forecast for Aha Rivermouth over the next 16 days.
The Lowdown
Right then, let’s see what we’ve got for Aha Rivermouth. The next two weeks are a bit of a mixed bag, but there’s a proper pulse of energy coming our way if you can wait for it.
We’re looking at a long, quiet start. For the first week and a half, the waves are just too small and the winds are messy, so don’t bother paddling out from August 13th through to the morning of the 22nd. It’s mostly cross-shore breezes and tiny dribble.
Then, from the morning of the 23rd of August, things change in a big way. A solid groundswell arrives. It’s coming from the ESE with a very long period of 16 seconds and 17 seconds. Swell heights start around 5ft, building to 8ft, and the combined swell energy jumps right up into the thousands, peaking at a massive 3298 on the 24th. That is a serious amount of power.
The real standouts are the 23rd afternoon through the 24th. On the 23rd afternoon, we’ve got a 7ft ESE swell with a 17-second period and glassy conditions—absolutely perfect if you can handle it. Then Monday the 24th is the best of it, with 8ft E swell, still a very long 16-second period, and totally glassy conditions both morning and afternoon. The waves will be clean and powerful.
The water temperature is around 83°, which is about average for the time of year, so don’t worry about a wetsuit.
Just a heads up: Aha Rivermouth is a beach and jetty setup. With that long period swell and that size—over 8ft—this is for experienced surfers only. Beginners, stay well clear. It’s going to be powerful, and the long period will mean clean lines but longer waits between sets. The break can get crowded sometimes too.
The 25th and 26th still offer good waves—8ft dropping to 6ft—with clean offshore winds from the W and WSW, but the swell energy begins to drop. By the 27th, it’s still a clean 5ft with offshore SW winds, but it’s losing its teeth. It’s not the main event.
All in all, if you can hold out, the 23rd afternoon and the 24th are your days. That Monday the 24th is the one to circle. Don’t sleep on it.
Rusty.
Short Range ForecastModerate rain (total 10mm), heaviest on Sat afternoon. Warm (max 28°C on Thu night, min 27°C on Thu night). Wind will be generally light. | Days 5-7 Weather SummaryMostly dry. Warm (max 28°C on Tue afternoon, min 27°C on Sun night). Mainly fresh winds. | ||||||||||||||||||
Friday 14 | Saturday 15 | Sunday 16 | Monday 17 | Tuesday 18 | Wednesday 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) | ENE 10 | ENE 10 | ENE 10 | ENE 9 | ENE 11 | ENE 11 | ENE 10 | ENE 10 | ENE 10 | ENE 10 | ENE 10 | ENE 10 | ENE 10 | ENE 10 | E 9 | E 6 | E 6 | ENE 9 | E 6 |
Wave Graph  | |||||||||||||||||||
 kJ | 78 | 38 | 35 | 28 | 93 | 101 | 90 | 90 | 78 | 78 | 104 | 102 | 74 | 72 | 241 | 112 | 120 | 197 | 138 |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | cross-on | cross-on | cross | cross | cross | cross | cross | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on |
High Tide | 7:20AM2.16m | 8:06PM2.05m | 8:00AM2.13m | 8:34PM2.06m | 8:38AM2.05m | 9:03PM2.03m | 9:16AM1.92m | 9:31PM1.98m | 9:55AM1.76m | 9:58PM1.91m | 10:38AM1.58m | 10:27PM1.82m | |||||||
Low Tide | 1:25AM0.67m | 1:49PM0.20m | 2:01AM0.58m | 2:21PM0.30m | 2:37AM0.53m | 2:51PM0.43m | 3:14AM0.53m | 3:20PM0.59m | 3:52AM0.57m | 3:47PM0.76m | 4:34AM0.65m | 4:13PM0.94m | |||||||
 |  |  |  | | | | |  | | | | | | |  | | | | |
 | — | 5:56 | — | — | 5:58 | — | — | 5:58 | — | — | 5:58 | — | — | 5:58 | — | — | 6:00 | — | — |
 | 7:06 | — | 7:05 | — | — | 7:04 | — | — | 7:02 | — | — | 7:01 | — | — | 7:00 | — | — | 7:00 | — |
mm | — | — | 1 | 2 | 1 | 3 | 3 | — | — | — | — | — | — | — | — | — | — | — | 4 |
Temp °C | 28 | 28 | 28 | 28 | 28 | 28 | 27 | 28 | 28 | 27 | 27 | 27 | 27 | 27 | 28 | 27 | 27 | 27 | 27 |
Feels °C | 33 | 33 | 32 | 32 | 31 | 31 | 28 | 29 | 29 | 28 | 29 | 28 | 28 | 28 | 29 | 28 | 27 | 27 | 28 |
Swell 1 Height (m) Direction Period (s) | S 8 | S 9 | S 8 | S 8 | S 8 | S 8 | ENE 10 | ENE 10 | ENE 10 | ENE 10 | ENE 10 | ENE 10 | ENE 10 | ENE 10 | SW 9 | SSW 8 | SSW 8 | SE 6 | SSW 8 |
| kJ | 49 | 73 | 66 | 45 | 65 | 63 | 90 | 90 | 78 | 78 | 104 | 102 | 74 | 72 | 21 | 20 | 21 | 31 | 7 |
Swell 2 Height (m) Direction Period (s) | ENE 10 | SW 8 | ENE 10 | ENE 9 | ENE 11 | ENE 11 | S 8 | S 8 | S 8 | SW 9 | SW 8 | SW 9 | SW 9 | SW 9 | SSW 9 | SW 9 | SW 9 | SSW 9 | S 9 |
| kJ | 78 | 33 | 35 | 28 | 93 | 101 | 43 | 30 | 29 | 41 | 35 | 36 | 28 | 20 | 15 | 12 | 3 | 15 | 7 |
Swell 3 Height (m) Direction Period (s) | SW 8 | ENE 10 | SW 8 | ENE 11 | E 4 | SW 8 | SW 9 | SW 8 | SW 9 | S 8 | ESE 11 | ESE 11 | S 7 | S 7 | S 7 | ESE 10 | ESE 10 | S 8 | SW 9 |
| kJ | 23 | 38 | 24 | 24 | 4 | 11 | 13 | 25 | 27 | 18 | 11 | 11 | 17 | 9 | 4 | 10 | 10 | 5 | 3 |
Wind waves Height (m) Direction Period (s) | — | — | — | — | — | E 5 | ESE 5 | SE 5 | SE 5 | ESE 4 | SE 5 | SE 7 | ESE 5 | ESE 5 | E 9 | E 6 | E 6 | ENE 9 | E 6 |
| kJ | — | — | — | — | — | 7 | 30 | 23 | 22 | 24 | 30 | 54 | 17 | 26 | 241 | 112 | 120 | 197 | 138 |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 12 | 68 | 68 | 12 | 12 | 12 | 12 | 12 | 70 | 70 | 68 | 70 | 70 | 68 | 68 | 68 | 68 | 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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