
Surf Forecasts:
Monabe Rivermouth surf forecast from 1 Aug 2026:
- Best quality surf: Thursday 6 Aug, 3AM (local time) - 23ft (7.0m), 17s period, SE swell with cross-offshore winds.
- Most powerful swell: Thursday 6 Aug, 6AM (local time) - 23ft (7.0m), 17s period, SE swell with 29,729 kJ wave energy.
- Next surfable swell (1★+): Sunday 2 Aug, 6AM (local time) - 2ft (0.6m), 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 Sunday (Aug 02) at 6AM. The primary swell is predicted to be 0.6m and 16s period with a secondary swell of 0.3m and 11s. Another secondary swell of 0.3m and 8s is also forecast. The wind is predicted to be offshore as the swell arrives.
The most powerful waves expected at Monabe Rivermouth in the next 16 days are 7.0m 17s and forecast to arrive on Thursday (Aug 06) at 6AM. Winds are predicted to be cross-offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.7m 5s period and expected on Sunday (Aug 02) at 3PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 6AM (Sun 2nd Aug) | 2ft (0.6m) 16s |
| Best Surf | 3AM (Thu 6th Aug) | 23ft (7.0m) 17s |
| Most Powerful | 6AM (Thu 6th Aug) | 23ft (7.0m) 17s |
Table - best surf conditions forecast for Monabe Rivermouth over the next 16 days.
The Lowdown
G’day, I’m Rusty, and I’ve got the lowdown on your local stretch for the next couple of weeks. We’re looking at a real mixed bag here, but there’s a proper window of power later on if you’ve got the patience.
First up, the name of the game here is Monabe Rivermouth. It’s a river break that’s rarely breaking, so when it does switch on, you’ve got to be on it. The water temp is sitting at 84°F; that’s a touch warmer than normal for this time of year, so you can leave the thick wetsuit at home.
The opening weekend is a bit of a slow burner. Saturday, 1 August, has tiny 1ft surf from the ESE with a period of 10 seconds. The wave energy is weak (43), and the conditions are pretty poor. Sunday the 2nd shows a bit more life with 2ft to 4ft ESE swell, and the period jumps to a very long 18 seconds in the morning. The combined energy is moderate (396) then strong (602) by the afternoon, but the wind is onshore, so it’s messy. The best chance on Sunday is the glassy morning, with that 2ft and 18-second period; it’s surfable, but pretty ordinary.
Monday the 3rd sees the swell building to 5ft, with a long 16-second period, but the wind is onshore, and there’s a risk of thunderstorms. The energy is ramping up (1292 to 1781), but the quality is poor. Tuesday the 4th gets bigger, with 8ft to 10ft ESE swell, 17-second period, and strong energy (4315 to 5940). The wind is cross-onshore, so it’s lumpy and marginal at best.
Now, here’s the standout. Wednesday, 5 August morning is the absolute pick of the whole forecast. You’ve got a solid 16ft of ESE swell with a very long 17-second period. The energy is massive (16162), and it’s glassy. That’s excellent surf conditions for experienced surfers. This is a big, powerful, clean groundswell pouring in. The size is over 8ft, so this is strictly for experts. The long period means it’ll hold up well at the rivermouth, but it’s going to be a handful. The afternoon on Wednesday gets ruined by strong 25 km/h (16 mph) cross-onshore winds, so don’t be late.
The rest of the first week is a brutal comedown. Thursday the 6th and Friday the 7th still have big, powerful swell (18ft to 23ft, 16-17 seconds, very strong energy), but the wind is cross-shore all day, making it marginal and choppy. Saturday the 8th morning is still 13ft with a 14-second period, but that afternoon the swell drops to 6ft and the period crashes to 8 seconds, with onshore winds making it a total write-off.
From Sunday 9 August through to the end of the second week, it’s a long stretch of poor to marginal conditions. The swell hovers between 3ft and 7ft, with periods mostly between 8 and 13 seconds. The energy is low to moderate, and the wind is almost always cross or cross-onshore. There’s a glimmer of hope on the morning of Saturday 15 August, with 5ft, 13-second period E swell, and glassy conditions, but it’s only rated as “good” and not a standout. The real recovery looks like Sunday 16 August morning, with 8ft, 14-second period E swell, glassy, and very good conditions. The energy is strong (2962). That’s a solid end to the forecast for experienced surfers, but it’s 16 days away, so keep an eye on it.
Rusty.
Short Range ForecastModerate rain (total 11mm), heaviest on Mon afternoon. Warm (max 33°C on Sun morning, min 26°C on Mon night). Wind will be generally light. | Days 4-6 Weather SummaryMostly dry. Warm (max 32°C on Wed morning, min 25°C on Tue night). Wind will be generally light. | ||||||||||||||||||||
Saturday 1 | Sunday 2 | Monday 3 | Tuesday 4 | Wednesday 5 | Thursday 6 | Friday 7 | |||||||||||||||
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 10 | SE 10 | ESE 16 | ESE 18 | ESE 16 | ESE 15 | ESE 16 | ESE 16 | ESE 18 | ESE 17 | ESE 17 | ESE 18 | ESE 17 | SE 18 | SE 17 | SE 17 | SE 16 | SSE 15 | S 16 | S 16 | S 15 |
Wave Graph | |||||||||||||||||||||
42 | 28 | 100 | 240 | 568 | 696 | 1151 | 1447 | 3393 | 3831 | 5183 | 12262 | 16162 | 20777 | 27367 | 27782 | 20451 | 15741 | 16041 | 13769 | 9375 | |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | glassy | on | off | glassy | on | glassy | on | cross-on | cross | cross-on | cross-on | off | glassy | cross-on | cross-off | cross | cross | cross-off | cross | cross | cross-off |
High Tide | 8:03PM1.77m | 7:40AM1.75m | 8:28PM1.77m | 8:20AM1.68m | 8:54PM1.75m | 9:05AM1.58m | 9:23PM1.72m | 10:00AM1.47m | 9:57PM1.67m | 11:18AM1.36m | 10:41PM1.60m | 1:19PM1.32m | 11:46PM1.54m | ||||||||
Low Tide | 1:34PM0.21m | 1:51AM0.67m | 2:03PM0.30m | 2:26AM0.61m | 2:33PM0.43m | 3:05AM0.57m | 3:05PM0.59m | 3:51AM0.55m | 3:42PM0.77m | 4:49AM0.54m | 4:29PM0.96m | 6:05AM0.52m | 5:47PM1.13m | ||||||||
5:16 | — | — | 5:16 | — | — | 5:16 | — | — | 5:18 | — | — | 5:18 | — | — | 5:20 | — | — | 5:20 | — | — | |
— | 7:05 | — | — | 7:04 | — | — | 7:02 | — | — | 7:01 | — | — | 7:01 | — | — | 7:00 | — | — | 7:00 | — | |
mm | — | — | — | — | — | — | 1 | 8 | 2 | — | — | — | — | — | — | — | — | — | — | — | — |
Temp °C | 31 | 31 | 28 | 33 | 31 | 29 | 31 | 29 | 27 | 27 | 27 | 26 | 32 | 32 | 27 | 32 | 32 | 28 | 32 | 32 | 27 |
Feels °C | 34 | 34 | 32 | 36 | 35 | 34 | 33 | 32 | 31 | 31 | 30 | 31 | 34 | 32 | 30 | 32 | 32 | 31 | 32 | 32 | 30 |
Swell 1 Height (m) Direction Period (s) | ESE 10 | SE 10 | ESE 16 | ESE 18 | ESE 16 | ESE 15 | ESE 16 | ESE 16 | ESE 18 | ESE 17 | ESE 17 | ESE 18 | ESE 17 | SE 18 | SE 17 | SE 17 | SE 16 | SSE 15 | S 16 | S 16 | S 15 |
42 | 28 | 100 | 240 | 568 | 696 | 1151 | 1447 | 3393 | 3831 | 5183 | 12262 | 16162 | 20777 | 27367 | 27782 | 20451 | 15741 | 16041 | 13769 | 9375 | |
Swell 2 Height (m) Direction Period (s) | SSW 4 | SW 6 | SE 11 | SE 9 | ENE 4 | SE 10 | SSE 10 | E 15 | SE 14 | — | — | — | — | — | — | — | — | — | — | — | E 15 |
3 | 5 | 19 | 40 | 6 | 15 | 10 | 17 | 8 | — | — | — | — | — | — | — | — | — | — | — | 17 | |
Swell 3 Height (m) Direction Period (s) | S 7 | S 4 | ESE 9 | ESE 14 | SE 10 | SSW 8 | S 8 | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
1 | 1 | 8 | 116 | 28 | 6 | 5 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | |
Wind waves Height (m) Direction Period (s) | — | — | — | NE 4 | NE 5 | — | ESE 6 | ESE 7 | ESE 8 | ESE 8 | ESE 9 | — | — | — | — | — | — | — | — | — | E 10 |
— | — | — | 9 | 21 | — | 126 | 317 | 438 | 484 | 757 | — | — | — | — | — | — | — | — | — | 96 | |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 491 | 490 | 9 | 0 | 42 | 0 | 20 | 335 | 20 | 20 | 20 | 0 | 0 | 515 | 0 | 387 | 531 | 0 | 531 | 531 | 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.











