Surf Forecasts:
Monabe Rivermouth surf forecast from 23 Aug 2026:
- Best quality surf: Tuesday 25 Aug, 12AM (local time) - 10ft (3.0m), 16s period, SE swell with offshore winds.
- Most powerful swell: Tuesday 25 Aug, 12PM (local time) - 11ft (3.5m), 15s period, SSE swell with 4,902 kJ wave energy.
- Next surfable swell (1★+): Monday 24 Aug, 6AM (local time) - 2ft (0.6m), 17s period with SE swell.
Best Forecast Surf Conditions for Monabe Rivermouth this week:
The surf forecast for Monabe Rivermouth over the next 16 days: The first swell (rated 1 star or higher) is forecast to arrive on Monday (Aug 24) at 6AM. The primary swell is predicted to be 0.6m and 17s period with a secondary swell of 0.7m and 13s. The wind is predicted to be glassy as the swell arrives.
The most powerful waves expected at Monabe Rivermouth in the next 16 days are 3.5m 15s and forecast to arrive on Tuesday (Aug 25) at 12PM. Winds are predicted to be onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.8m 11s period and expected on Wednesday (Aug 26) at 9PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 6AM (Mon 24th Aug) | 2ft (0.6m) 17s |
| Best Surf | 12AM (Tue 25th Aug) | 10ft (3.0m) 16s |
| Most Powerful | 12PM (Tue 25th Aug) | 11ft (3.5m) 15s |
Table - best surf conditions forecast for Monabe Rivermouth over the next 16 days.
The Lowdown
Alright, Rusty here, looking at what we’ve got for the Monabe Rivermouth over the next couple of weeks.
First off, the water temp is sitting about average for the time of year, nothing crazy there. This setup is a river mouth that rarely breaks, so when it does, you gotta pay attention. The direction it likes is east, which is pretty specific.
It's a slow start. Monday the 24th shows a little 4ft SE swell with a very long 19-second period and glassy conditions in the morning, wave energy is moderate at (1023). That's clean, but the size is small for the period. Tuesday the 25th is the real standout for experienced surfers. We’ve got a strong 10ft SSE groundswell, 14-second period, and full-on glassy conditions in the morning with calm wind. Wave energy is pumping at (5220). That’s going to be big, powerful, and clean. Because it’s a river mouth, that long-period swell should wrap in nicely. Crowds are possible here, so get in early. This is too big for beginners though.
Wednesday the 26th morning is still good, with a 8ft S swell and glassy conditions, energy is high (2643), but the afternoon turns onshore. From Thursday the 27th through the end of the month, it drops right off – tiny, weak swells and ordinary conditions, mostly poor. There’s a long gap of small, unremarkable surf from the 28th of August right through to the 1st of September.
Into the new week, Monday the 1st of September has a slight uptick with a 4ft S swell and clean calm conditions, but it’s just ordinary. Tuesday the 2nd of September morning shows some hope with a 6ft S swell and a light offshore NNW wind, making it clean, but still just surfable, nothing special.
The next real highlight is Sunday the 7th of September morning. We’ve got a 7ft S swell with a 13-second period and completely glassy, calm conditions. Wave energy is solid at (1459). This is another promising window – clean, shoulder-high to overhead surf. That will be one to watch as it gets closer. Monday the 8th of September morning looks similar with another 7ft S swell and glassy conditions. Good potential for a run of decent waves early in the second week.
Overall, don't waste your time on the first week except for Tuesday the 25th, which is the real beast. The second week has a couple of good-looking mornings that could clean up nicely.
Rusty.
Short Range ForecastMostly dry. Warm (max 30°C on Wed morning, min 25°C on Sun night). Wind will be generally light. | Days 5-7 Weather SummaryLight rain (total 4mm), mostly falling on Wed night. Warm (max 29°C on Fri morning, min 26°C on Wed night). Wind will be generally light. | ||||||||||||||||||
Monday 24 | Tuesday 25 | Wednesday 26 | Thursday 27 | Friday 28 | Saturday 29 | ||||||||||||||
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) | SE 12 | SE 19 | SE 16 | SE 16 | SSE 14 | SSE 14 | S 14 | S 13 | S 12 | SE 9 | SSE 9 | SSE 9 | SSE 9 | SE 8 | E 13 | S 9 | S 8 | S 8 | S 8 |
Wave Graph  | |||||||||||||||||||
 kJ | 120 | 808 | 2269 | 4417 | 3052 | 3501 | 4324 | 2382 | 1575 | 294 | 371 | 343 | 238 | 98 | 53 | 318 | 205 | 165 | 173 |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | glassy | glassy | on | off | glassy | on | off | glassy | on | cross-off | glassy | glassy | glassy | glassy | on | glassy | glassy | cross-on | glassy |
High Tide | 2:38AM1.41m | 5:10PM1.53m | 3:40AM1.52m | 5:30PM1.61m | 4:25AM1.63m | 5:51PM1.69m | 5:03AM1.74m | 6:12PM1.76m | 5:39AM1.81m | 6:34PM1.80m | 6:14AM1.86m | 6:56PM1.84m | |||||||
Low Tide | 9:54PM1.19m | 9:59AM0.46m | 10:30PM1.08m | 10:37AM0.35m | 10:58PM0.96m | 11:10AM0.25m | 11:25PM0.84m | 11:40AM0.20m | 11:53PM0.72m | 12:08PM0.18m | 00:21AM0.60m | 12:37PM0.21m | 00:51AM0.50m | ||||||
 |  | | | | | | | |  |  |  |  |  | | |  | | | |
 | — | 5:31 | — | — | 5:33 | — | — | 5:33 | — | — | 5:33 | — | — | 5:35 | — | — | 5:35 | — | — |
 | 6:42 | — | 6:40 | — | — | 6:39 | — | — | 6:38 | — | — | 6:37 | — | — | 6:36 | — | — | 6:35 | — |
mm | — | — | — | — | — | — | — | — | — | 1 | 2 | — | — | 1 | — | — | — | — | — |
Temp °C | 27 | 29 | 29 | 27 | 29 | 29 | 26 | 30 | 30 | 28 | 28 | 28 | 27 | 29 | 29 | 27 | 29 | 29 | 27 |
Feels °C | 33 | 33 | 33 | 32 | 31 | 32 | 30 | 34 | 34 | 33 | 34 | 34 | 32 | 33 | 32 | 33 | 32 | 33 | 33 |
Swell 1 Height (m) Direction Period (s) | SE 12 | SE 19 | SE 16 | SE 16 | SSE 14 | SSE 14 | S 14 | S 13 | S 12 | SSW 11 | SSE 9 | SSE 9 | SSE 9 | SSW 9 | SSW 9 | S 9 | S 8 | S 8 | S 8 |
| kJ | 120 | 808 | 2269 | 4417 | 3052 | 3501 | 4324 | 2382 | 1575 | 731 | 371 | 343 | 238 | 294 | 294 | 318 | 205 | 165 | 173 |
Swell 2 Height (m) Direction Period (s) | SSW 8 | SE 12 | E 12 | E 16 | SSE 16 | S 17 | E 14 | SE 10 | E 13 | SE 9 | SSW 11 | SSW 10 | SSW 9 | SE 8 | SE 7 | E 12 | E 12 | E 12 | E 12 |
| kJ | 47 | 139 | 47 | 20 | 2061 | 1405 | 91 | 177 | 82 | 202 | 469 | 260 | 172 | 98 | 50 | 74 | 44 | 43 | 23 |
Swell 3 Height (m) Direction Period (s) | S 8 | E 12 | S 8 | E 16 | E 15 | E 14 | — | E 13 | E 13 | E 12 | E 12 | E 12 | S 8 | ESE 11 | E 13 | SW 12 | SW 11 | SW 12 | SE 11 |
| kJ | 22 | 76 | 20 | 20 | 107 | 103 | — | 84 | 82 | 73 | 44 | 44 | 47 | 38 | 53 | 21 | 20 | 21 | 19 |
Wind waves Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | SE 9 | — | — | — | — | — | — | — | SW 3 | — |
| kJ | — | — | — | — | — | — | — | — | — | 294 | — | — | — | — | — | — | — | 3 | — |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 9 | 0 | 42 | 0 | 0 | 50 | 0 | 0 | 20 | 0 | 0 | 0 | 0 | 9 | 42 | 0 | 0 | 42 | 0 |
Best forecast wave conditions in Shikoku | |||||||||||||||||||
Best forecast wave conditions in Japan | |||||||||||||||||||
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Information about the Monabe Rivermouth Surf forecast
The above surf forecast table for Monabe Rivermouth provides essential information for determining whether the surfing conditions will be good over the next 16 days. A general guide to surfing at Monabe Rivermouth can be found by selecting the local surf guide option on the grey menu. Our Monabe 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 (Monabe 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 Monabe 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.
Monabe Rivermouth is 11 km (7 miles) from the city of Aki. If you plan a holiday in Shikoku, look for hotels and other accommodation in Aki. Aki has rooms for a wide range of budgets as well as car hire and transport links.
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