Surf Forecasts:
Monabe Rivermouth surf forecast from 9 Aug 2026:
- Best quality surf: Monday 10 Aug, 3AM (local time) - 4.5ft (1.3m), 13s period, E swell with glassy winds.
- Most powerful swell: Sunday 9 Aug, 12PM (local time) - 4.5ft (1.4m), 13s period, E swell with 694 kJ wave energy.
- Next surfable swell (1★+): Sunday 9 Aug, 6PM (local time) - 4.5ft (1.4m), 13s period with E 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 Sunday (Aug 09) at 6PM. The primary swell is predicted to be 1.4m and 13s period. 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 1.4m 13s and forecast to arrive on Sunday (Aug 09) 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 12s period and expected on Sunday (Aug 09) at 12PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 6PM (Sun 9th Aug) | 4.5ft (1.4m) 13s |
| Best Surf | 3AM (Mon 10th Aug) | 4.5ft (1.3m) 13s |
| Most Powerful | 12PM (Sun 9th Aug) | 4.5ft (1.4m) 13s |
Table - best surf conditions forecast for Monabe Rivermouth over the next 16 days.
The Lowdown
Alright, Rusty here again, but in feet and miles.
So, the next 16 days are patchy, you gotta be smart. The best surf is Sunday morning (9 August) at Monabe Rivermouth. That spot is a river mouth, very sheltered, and it hardly ever breaks, so when it does, get on it. Sunday morning you’ll see waves around 4ft from the ESE with a 13-second period – that’s real groundswell. Water temp is 84°, a touch warmer than normal. The energy in the water is moderate, about 730. Wind is glassy out of the south at just 3 mph, so the surface will be clean. Not huge, but for a spot that’s inconsistent, this is your best bet.
Sunday afternoon brings a risk of thunderstorms and shifting wind, so don’t push it. Monday morning (10 August) offers another chance with 4ft from the east, 12-second period, and glassy conditions early – energy around 727. Still surfable but not as good as Sunday.
Then it goes dead quiet from Tuesday (11 August) through to Friday (14 August) morning. Swell drops to under 3ft, periods under 11 seconds, energy in the low hundreds. Not worth it. Friday morning (14 August) shows a little bump with 3ft from the east, 9-second period, and glassy wind, but it’s still ordinary.
The next real window is Saturday 22 August morning – a new pulse from the south, 4ft with an 11-second period, energy of 428, and glassy conditions. That’s promising. Sunday 23 August morning looks even better with 4ft from the south, 11-second period, energy 553, and calm winds. That’s the second best – clean glass, a bit more size, but still not a firing day.
This break rarely breaks, and crowds are sometimes a thing. For this size, it’s fine for intermediates – over 5ft is too much for beginners, and over 8ft is expert territory. The long period (over 11 seconds) means better shape and longer lulls between sets, which helps with paddling out, but at a river mouth the waves can get a bit walled.
About 12 days between the good windows, so it’s a quiet stretch. Sunday morning is the pick. After that, wait for the 22nd and 23rd.
Rusty.
Short Range ForecastLight rain (total 3mm), mostly falling on Sun afternoon. Warm (max 29°C on Sun morning, min 22°C on Tue night). Wind will be generally light. | Days 4-6 Weather SummaryModerate rain (total 15mm), heaviest on Thu afternoon. Warm (max 28°C on Wed morning, min 23°C on Wed night). Wind will be generally light. | ||||||||||||||||||||
Sunday 9 | Monday 10 | Tuesday 11 | Wednesday 12 | Thursday 13 | Friday 14 | Saturday 15 | |||||||||||||||
AM | 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) | ESE 13 | E 13 | E 13 | E 12 | E 12 | E 12 | E 11 | E 11 | E 10 | E 10 | E 10 | S 9 | E 10 | E 10 | E 9 | E 9 | E 9 | E 10 | E 10 | E 10 | ESE 11 |
Wave Graph  | |||||||||||||||||||||
 kJ | 617 | 683 | 673 | 437 | 350 | 278 | 155 | 191 | 130 | 106 | 52 | 83 | 30 | 28 | 26 | 168 | 104 | 121 | 100 | 100 | 146 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | glassy | on | glassy | glassy | on | glassy | glassy | on | off | glassy | on | cross-off | cross-on | cross | off | glassy | glassy | cross-off | glassy | on | off |
High Tide | 4:31PM1.57m | 2:49AM1.60m | 5:17PM1.70m | 3:58AM1.71m | 5:54PM1.79m | 4:53AM1.82m | 6:28PM1.85m | 5:42AM1.90m | 6:59PM1.87m | 6:27AM1.93m | 7:27PM1.86m | 7:10AM1.89m | 7:54PM1.84m | ||||||||
Low Tide | 9:02AM0.31m | 9:40PM1.16m | 10:06AM0.16m | 10:38PM1.05m | 10:58AM0.04m | 11:23PM0.92m | 11:43AM-0.03m | 00:02AM0.79m | 12:23PM-0.02m | 00:40AM0.67m | 1:00PM0.06m | 1:16AM0.57m | 1:33PM0.19m | 1:52AM0.51m | |||||||
 |  |  | | |  |  | | | |  | | | |  | | | | | | | |
 | 5:22 | — | — | 5:22 | — | — | 5:22 | — | — | 5:24 | — | — | 5:24 | — | — | 5:24 | — | — | 5:26 | — | — |
 | — | 6:58 | — | — | 6:57 | — | — | 6:55 | — | — | 6:54 | — | — | 6:53 | — | — | 6:52 | — | — | 6:52 | — |
mm | — | 2 | — | — | 1 | — | — | — | — | — | 1 | — | 2 | 7 | 4 | — | 1 | — | — | — | 2 |
Temp °C | 29 | 28 | 26 | 29 | 29 | 26 | 29 | 29 | 25 | 28 | 27 | 26 | 27 | 26 | 24 | 28 | 26 | 24 | 28 | 28 | 25 |
Feels °C | 32 | 31 | 30 | 32 | 33 | 30 | 30 | 31 | 27 | 28 | 29 | 29 | 29 | 27 | 27 | 30 | 29 | 27 | 30 | 31 | 29 |
Swell 1 Height (m) Direction Period (s) | SSW 12 | SSW 12 | SSW 11 | E 12 | E 12 | S 10 | SSW 10 | SSW 10 | SSW 11 | SSW 10 | SSW 10 | SSW 10 | SSW 9 | SSW 9 | SSW 9 | SSW 9 | SSW 9 | E 10 | E 10 | SSW 10 | SSW 9 |
| kJ | 923 | 857 | 724 | 437 | 350 | 264 | 312 | 312 | 359 | 276 | 236 | 127 | 156 | 113 | 110 | 108 | 82 | 121 | 100 | 125 | 115 |
Swell 2 Height (m) Direction Period (s) | ESE 13 | E 13 | E 13 | S 10 | S 10 | E 12 | E 11 | E 11 | E 10 | E 10 | E 10 | S 9 | E 10 | E 10 | E 5 | E 9 | SE 11 | SSW 9 | SSW 8 | E 10 | ESE 11 |
| kJ | 617 | 683 | 673 | 290 | 239 | 278 | 155 | 191 | 130 | 106 | 52 | 83 | 30 | 28 | 11 | 78 | 19 | 79 | 75 | 100 | 146 |
Swell 3 Height (m) Direction Period (s) | SE 8 | SE 8 | ESE 15 | SW 11 | SW 11 | SW 10 | SE 13 | SE 13 | SE 13 | SE 13 | S 10 | E 10 | SE 12 | SE 12 | E 9 | SE 11 | SE 16 | SE 11 | SE 11 | SE 10 | E 10 |
| kJ | 113 | 55 | 21 | 145 | 172 | 108 | 27 | 27 | 27 | 27 | 31 | 32 | 23 | 22 | 26 | 20 | 10 | 30 | 71 | 79 | 94 |
Wind waves Height (m) Direction Period (s) | — | — | — | — | — | — | NE 5 | NE 5 | NE 5 | ENE 4 | ENE 3 | E 4 | E 4 | E 5 | — | E 9 | E 9 | — | — | — | — |
| kJ | — | — | — | — | — | — | 8 | 20 | 18 | 1 | 2 | 9 | 16 | 27 | — | 168 | 104 | — | — | — | — |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 0 | 50 | 0 | 0 | 42 | 0 | 9 | 53 | 9 | 9 | 20 | 9 | 20 | 335 | 9 | 0 | 9 | 9 | 9 | 75 | 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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