Surf Forecasts:
Monabe Rivermouth surf forecast from 8 Aug 2026:
- Best quality surf: Monday 10 Aug, 6AM (local time) - 4.5ft (1.3m), 13s period, E swell with offshore winds.
- Most powerful swell: Sunday 9 Aug, 12PM (local time) - 4.5ft (1.4m), 13s period, E swell with 704 kJ wave energy.
- Next surfable swell (1★+): Saturday 8 Aug, 9PM (local time) - 3.5ft (1.1m), 10s 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 Saturday (Aug 08) at 9PM. The primary swell is predicted to be 1.1m and 10s period with a secondary swell of 1.2m and 8s. The wind is predicted to be cross-offshore 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 2.0m 12s period and expected on Sunday (Aug 09) at 6PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 9PM (Sat 8th Aug) | 3.5ft (1.1m) 10s |
| Best Surf | 6AM (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 mate, Rusty here. Let’s have a look at what’s on the cards for our local stretch.
Honestly, for the first week and a half, it’s pretty grim. We’ve got a long dry spell with no real quality on offer. The only spot that even gets a mention is Monabe Rivermouth, and it’s a fickle one – it *rarely breaks* as it is, so you’re really chasing a needle in a haystack here. The water is sitting at 85°, which is a touch warmer than normal for this time of year, so at least it’ll feel like a bath while you’re staring at flat lines.
The first real glimmer of hope doesn’t show up until Sunday the 16th of August. The morning looks like the standout of the entire outlook. We’ve got a solid 6ft swell rolling in from the east, with a long period of 11 seconds, bringing decent energy (933). The wind is glassy – dead calm – which is a massive positive for a rivermouth setup. That’s about as clean as it gets. This is the best window by a long shot. The swell is a bit much for beginners at that size, but for anyone with a bit of experience, it’s looking good. Just be aware that it’s a river mouth, so that long-period south-east groundswell can sometimes make things a bit straight, but with those conditions, it’s worth a paddle.
After that, things drop off again pretty quickly. The following Monday morning the 17th has some small 4ft east swell with glassy conditions, but it’s nothing to write home about. The rest of the second week is mostly small, weak, and messy, with a lot of cross-onshore wind and poor scores. There’s a bit of south-east swell showing up around the 21st and 22nd, but it’s all cross-onshore and choppy, not worth the drive.
So, to sum it up: if you’re hanging for a wave, your only real shot is Sunday morning the 16th of August. Get up early, get down to the rivermouth, and enjoy that clean, glassy 6ft east swell. The rest of the fortnight is a write-off.
Rusty.
Short Range ForecastSome drizzle, heaviest during Sun afternoon. Warm (max 30°C on Sat morning, min 25°C on Sat night). Wind will be generally light. | Days 4-6 Weather SummaryModerate rain (total 12mm), heaviest on Thu afternoon. Warm (max 28°C on Tue morning, min 23°C on Tue night). Wind will be generally light. | ||||||||||||||||||||
Saturday 8 | Sunday 9 | Monday 10 | Tuesday 11 | Wednesday 12 | Thursday 13 | Friday 14 | |||||||||||||||
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) | S 11 | SE 9 | SE 8 | ESE 13 | E 13 | E 13 | E 12 | E 12 | S 11 | E 11 | E 11 | E 10 | E 10 | E 10 | E 5 | E 6 | E 10 | E 5 | E 11 | E 11 | E 10 |
Wave Graph  | |||||||||||||||||||||
 kJ | 1213 | 440 | 214 | 617 | 683 | 673 | 437 | 350 | 319 | 155 | 151 | 102 | 51 | 32 | 41 | 74 | 34 | 35 | 223 | 55 | 71 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross | cross-on | off | glassy | on | cross-off | glassy | glassy | glassy | glassy | on | off | glassy | on | cross-off | glassy | cross-on | cross-off | glassy | cross | off |
High Tide | 3:23PM1.42m | 1:20AM1.53m | 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 | ||||||||
Low Tide | 8:01PM1.21m | 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 | ||||||||
 |  |  | |  |  | | | | | | | |  | | | |  | | | | |
 | 5:20 | — | — | 5:22 | — | — | 5:22 | — | — | 5:22 | — | — | 5:24 | — | — | 5:24 | — | — | 5:24 | — | — |
 | — | 6:59 | — | — | 6:58 | — | — | 6:57 | — | — | 6:55 | — | — | 6:54 | — | — | 6:53 | — | — | 6:52 | — |
mm | — | — | — | — | 1 | — | — | — | — | — | 1 | — | — | 1 | — | 2 | 4 | 4 | 1 | 5 | — |
Temp °C | 30 | 30 | 26 | 29 | 29 | 27 | 28 | 28 | 26 | 28 | 28 | 25 | 28 | 28 | 25 | 27 | 28 | 25 | 28 | 29 | 25 |
Feels °C | 30 | 30 | 30 | 32 | 32 | 32 | 32 | 32 | 30 | 30 | 31 | 29 | 30 | 30 | 28 | 28 | 30 | 28 | 31 | 32 | 28 |
Swell 1 Height (m) Direction Period (s) | S 11 | SSW 11 | SSW 11 | SSW 12 | SSW 12 | SSW 11 | S 10 | E 12 | S 11 | SSW 10 | SSW 10 | SSW 11 | SSW 11 | SSW 10 | SSW 10 | SSW 10 | SSW 10 | SSW 9 | SSW 9 | SSW 9 | S 8 |
| kJ | 1213 | 911 | 799 | 1018 | 939 | 750 | 347 | 350 | 319 | 392 | 400 | 423 | 423 | 339 | 260 | 209 | 193 | 149 | 138 | 110 | 66 |
Swell 2 Height (m) Direction Period (s) | E 15 | ESE 10 | SE 8 | ESE 13 | E 13 | E 13 | E 12 | S 10 | E 12 | E 11 | E 11 | E 10 | E 10 | E 10 | E 10 | E 10 | E 10 | E 5 | E 6 | E 11 | E 10 |
| kJ | 4 | 131 | 214 | 617 | 683 | 673 | 437 | 252 | 278 | 155 | 151 | 102 | 51 | 32 | 31 | 30 | 28 | 35 | 15 | 55 | 71 |
Swell 3 Height (m) Direction Period (s) | E 15 | SE 17 | E 9 | SE 8 | SSE 12 | ESE 15 | SW 11 | SSW 10 | SSW 11 | SE 13 | SE 13 | SE 13 | SE 13 | SE 13 | SE 12 | SE 12 | SE 12 | E 9 | E 10 | SE 11 | E 5 |
| kJ | 4 | 11 | 176 | 96 | 14 | 21 | 126 | 189 | 143 | 28 | 27 | 27 | 27 | 26 | 24 | 23 | 22 | 28 | 53 | 19 | 18 |
Wind waves Height (m) Direction Period (s) | ESE 9 | SE 9 | — | — | SE 7 | — | — | — | — | NE 4 | — | — | — | E 3 | E 5 | E 6 | E 5 | — | E 11 | E 5 | — |
| kJ | 666 | 440 | — | — | 89 | — | — | — | — | 4 | — | — | — | 2 | 41 | 74 | 34 | — | 223 | 19 | — |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 20 | 75 | 0 | 0 | 75 | 0 | 0 | 0 | 0 | 9 | 50 | 9 | 9 | 335 | 9 | 9 | 20 | 9 | 0 | 190 | 9 |
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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