
Surf Forecasts:
Monabe Rivermouth surf forecast from 4 Aug 2026:
- Best quality surf: Tuesday 4 Aug, 9PM (local time) - 13ft (4.0m), 16s period, ESE swell with glassy winds.
- Most powerful swell: Thursday 6 Aug, 12PM (local time) - 20ft (6.0m), 16s period, SE swell with 18,782 kJ wave energy.
- Next surfable swell (1★+): Tuesday 4 Aug, 9PM (local time) - 13ft (4.0m), 16s period with ESE 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 Tuesday (Aug 04) at 9PM. The primary swell is predicted to be 4.0m and 16s period with a secondary swell of 4.0m and 16s. 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 6.0m 16s and forecast to arrive on Thursday (Aug 06) at 12PM. Winds are predicted to be cross-shore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 5.0m 17s period and expected on Sunday (Aug 09) at 3AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 9PM (Tue 4th Aug) | 13ft (4.0m) 16s |
| Best Surf | 9PM (Tue 4th Aug) | 13ft (4.0m) 16s |
| Most Powerful | 12PM (Thu 6th Aug) | 20ft (6.0m) 16s |
Table - best surf conditions forecast for Monabe Rivermouth over the next 16 days.
The Lowdown
Alright, this is Rusty. Let’s have a look at what’s shaping up for the Monabe Rivermouth area.
Well, the first thing to say is that we’ve got some serious size coming in, but this spot is a tricky one. It’s a rivermouth and it rarely breaks, so when it does, it’s a special event, but you’ve got to nail the timing. The water is a touch warmer than normal for this time of year, coming in at 85°, so that’s a nice bonus.
The standout window is Wednesday, August 5th. We’re looking at a massive 15ft groundswell from the ESE with a very long 16 second period for the morning. The combined energy is a huge 11232, and the wind is dead calm – glassy. That’s a dream setup if you’re an experienced surfer. This is powerful, pulse-y stuff, and with that period, it’s going to be a bit straight at a beach break, but at a river mouth, it might just line up perfectly. The morning is the clear winner here. The afternoon holds even bigger 16ft swell, but the wind comes onshore and chops it up.
Before that, Tuesday, August 4th is a bit of a warm-up. The morning has an 8ft swell with a 16 second period, but it’s a risky one with thunderstorms and a cross-onshore breeze. The afternoon builds to 10ft, but the wind picks up. Not the best, but you can see the energy building.
After that Wednesday peak, the wind absolutely ruins things. From Thursday, August 6th right through to August 10th, we’ve got strong cross-shore winds, 15 to 21 mph, and lumpy, choppy conditions. The swell stays big, but the quality is gone. This would be much more interesting for kite surfing than a paddle session.
There’s a small window of relief on Tuesday, August 11th. The morning is glassy again with a 5ft swell, but the period is short at 8 seconds, so it’s weak and mushy. The combined energy is only 537. It’s surfable, but very ordinary.
Then we hit another dry spell. The 12th, 13th, and 14th are all small and uninspiring, with a couple of glassy moments but nothing with any punch. The 15th and 16th see a pulse of 10ft to 12ft swell, but it’s short period and onshore wind again – poor quality.
The last few days of the forecast, from the 17th to the 19th, are small and marginal. The bottom line is: if you’re an experienced surfer, Wednesday morning, August 5th is the only true standout. Get there early for the glass and the big, clean lines. Everything else is either blown out or too weak.
Rusty.
Short Range ForecastLight rain (total 2mm), mostly falling on Tue morning. Warm (max 33°C on Thu morning, min 25°C on Tue night). Wind will be generally light. | Days 4-6 Weather SummaryHeavy rain (total 36mm), heaviest during Sat night. Warm (max 31°C on Fri morning, min 26°C on Sat afternoon). Mainly fresh winds. | ||||||||||||||||||||
Tuesday 4 | Wednesday 5 | Thursday 6 | Friday 7 | Saturday 8 | Sunday 9 | Monday 10 | |||||||||||||||
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 16 | ESE 17 | ESE 16 | ESE 16 | ESE 16 | SE 16 | SE 16 | SE 16 | SSE 16 | SSE 16 | SSE 15 | S 16 | ESE 9 | ESE 10 | ESE 9 | ESE 9 | ESE 9 | ESE 9 | ESE 9 | ESE 9 | ESE 8 |
Wave Graph | |||||||||||||||||||||
3277 | 4757 | 9028 | 11232 | 13382 | 14807 | 17488 | 18752 | 17940 | 15451 | 12889 | 8880 | 1759 | 1840 | 1635 | 2078 | 2171 | 2448 | 2458 | 2041 | 1051 | |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | on | cross-off | glassy | cross-on | cross-off | cross | cross | cross-off | cross | cross | cross-off | cross | cross | cross | cross | cross | cross | cross | cross | cross |
High Tide | 9:05AM1.58m | 9:23PM1.72m | 10:00AM1.47m | 9:57PM1.67m | 11:18AM1.36m | 10:41PM1.60m | 1:19PM1.32m | 11:46PM1.54m | 3:23PM1.42m | 1:20AM1.53m | 4:31PM1.57m | 2:49AM1.60m | 5:17PM1.70m | ||||||||
Low Tide | 3:05PM0.59m | 3:51AM0.55m | 3:42PM0.77m | 4:49AM0.54m | 4:29PM0.96m | 6:05AM0.52m | 5:47PM1.13m | 7:38AM0.45m | 8:01PM1.21m | 9:02AM0.31m | 9:40PM1.16m | 10:06AM0.16m | 10:38PM1.05m | ||||||||
5:18 | — | — | 5:18 | — | — | 5:20 | — | — | 5:20 | — | — | 5:20 | — | — | 5:22 | — | — | 5:22 | — | — | |
— | 7:01 | — | — | 7:01 | — | — | 7:00 | — | — | 7:00 | — | — | 6:59 | — | — | 6:58 | — | — | 6:57 | — | |
mm | 2 | — | — | — | — | — | — | — | — | — | 1 | 1 | 2 | 5 | 19 | 7 | 1 | — | — | — | — |
Temp °C | 28 | 28 | 26 | 31 | 31 | 27 | 33 | 33 | 28 | 31 | 31 | 28 | 29 | 29 | 27 | 28 | 28 | 27 | 27 | 28 | 26 |
Feels °C | 32 | 32 | 30 | 34 | 33 | 30 | 32 | 32 | 29 | 30 | 31 | 29 | 30 | 29 | 28 | 28 | 28 | 26 | 25 | 27 | 27 |
Swell 1 Height (m) Direction Period (s) | ESE 16 | ESE 17 | ESE 16 | ESE 16 | ESE 16 | SE 16 | SE 16 | SE 16 | SSE 16 | SSE 16 | SSE 15 | S 16 | SSW 16 | SSW 16 | SSW 16 | SSW 17 | SSW 16 | SSW 16 | SSW 16 | SSW 14 | SSW 13 |
3277 | 4757 | 9028 | 11232 | 13382 | 14807 | 17488 | 18752 | 17940 | 15451 | 12889 | 8880 | 8318 | 8791 | 11734 | 12523 | 10147 | 9804 | 7224 | 5149 | 3074 | |
Swell 2 Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | — | — | — | — | — | ESE 16 | — | — | — | — | — | SSE 9 |
— | — | — | — | — | — | — | — | — | — | — | — | — | — | 51 | — | — | — | — | — | 264 | |
Swell 3 Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | E 12 |
— | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 244 | |
Wind waves Height (m) Direction Period (s) | ESE 8 | ESE 9 | — | — | — | — | — | — | — | — | ESE 10 | ESE 10 | ESE 9 | ESE 10 | ESE 9 | ESE 9 | ESE 9 | ESE 9 | ESE 9 | ESE 9 | ESE 8 |
509 | 724 | — | — | — | — | — | — | — | — | 2708 | 1657 | 1759 | 1840 | 1635 | 2078 | 2171 | 2448 | 2458 | 2041 | 1051 | |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 20 | 515 | 0 | 0 | 190 | 0 | 77 | 531 | 550 | 515 | 515 | 57 | 515 | 515 | 515 | 550 | 515 | 1044 | 1514 | 1510 | 426 |
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.











