
Surf Forecasts:
Monabe Rivermouth surf forecast from 6 Aug 2026:
- Best quality surf: Thursday 6 Aug, 9PM (local time) - 18ft (5.5m), 14s period, SE swell with cross-offshore winds.
- Most powerful swell: Thursday 6 Aug, 3PM (local time) - 18ft (5.5m), 15s period, SE swell with 12,237 kJ wave energy.
- Next surfable swell (1★+): Thursday 6 Aug, 9PM (local time) - 18ft (5.5m), 14s 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 Thursday (Aug 06) at 9PM. The primary swell is predicted to be 5.5m and 14s period with a secondary swell of 5.0m and 14s. 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 5.5m 15s and forecast to arrive on Thursday (Aug 06) at 3PM. Winds are predicted to be cross-shore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 2.5m 12s period and expected on Saturday (Aug 08) at 9AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 9PM (Thu 6th Aug) | 18ft (5.5m) 14s |
| Best Surf | 9PM (Thu 6th Aug) | 18ft (5.5m) 14s |
| Most Powerful | 3PM (Thu 6th Aug) | 18ft (5.5m) 15s |
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 coming up at Monabe Rivermouth.
Honestly, the next couple of weeks are a tough watch. We’ve got some serious size coming through, especially early on, but the conditions are going to be a mess for most of it. This is a river-mouth setup that's very sheltered, and it needs everything to line up just right to be any good. The opening days, August 6th and 7th, are the main event in terms of swell size – we're talking a solid 16ft to 18ft of south-east groundswell rolling in, with a long 14 to 15-second period. That's a lot of water moving around, with the combined energy hitting some big numbers (12,237 at its peak). But the wind is blowing straight across it from the east, so it’ll be lumpy and chopped up. The water temperature is sitting at a balmy 85°, which is a touch warmer than normal for this time of year.
The standout window, and really the only time it looks worth paddling out, is the morning of Sunday, August 9th. The swell drops right back to a much more manageable 4ft from the east, with that same long 13-second period. More importantly, the wind goes glassy out of the south-east. That’s clean, smooth conditions. The energy is moderate (850), but for this spot, that glassy surface is gold. It won't be the biggest you've ever surfed, but it'll be the best quality you'll see. The only catch is this break rarely breaks at all, and even then it's only for intermediates. Don't expect perfection, but conditions will be better.
After that Sunday morning, it’s a slow fade into a long, flat spell. From the afternoon of the 9th all the way through to the 21st of August, the swell drops under 5ft, often sitting below 3ft. The wind is mostly onshore or cross-onshore, and nearly every session is rated as poor. There are a few glassy mornings in there, like the 13th and 15th, but the swell is too small and weak to do much with. It’s a long stretch of quiet water. The 19th and 20th mornings show a little bump back up to 4-5ft, but the wind is light and onshore, so it’ll be bumpy. Nothing here to get excited about.
So, bottom line: if you want the best of what’s on offer, you’re looking at the glassy Sunday morning, August 9th. Get on it early. The rest is a waiting game.
- Rusty
Short Range ForecastHeavy rain (total 21mm), heaviest during Fri morning. Warm (max 33°C on Thu morning, min 24°C on Sat night). Wind will be generally light. | Days 4-6 Weather SummaryMostly dry. Warm (max 29°C on Sun morning, min 25°C on Sun night). Wind will be generally light. | ||||||||||||||||||||
Thursday 6 | Friday 7 | Saturday 8 | Sunday 9 | Monday 10 | Tuesday 11 | Wednesday 12 | |||||||||||||||
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) | SE 14 | SE 15 | SE 14 | SE 13 | SE 12 | S 12 | ESE 9 | ESE 9 | SE 8 | E 13 | E 13 | S 12 | E 13 | E 12 | S 11 | E 11 | E 11 | E 11 | E 10 | S 11 | E 10 |
Wave Graph | |||||||||||||||||||||
10174 | 12237 | 10352 | 6277 | 4493 | 2096 | 929 | 826 | 428 | 506 | 653 | 1066 | 451 | 347 | 632 | 152 | 114 | 81 | 51 | 182 | 65 | |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross | cross | cross-off | cross | cross | cross-off | cross | cross-on | glassy | glassy | cross-on | cross-off | cross-on | on | off | glassy | cross-on | glassy | glassy | on | off |
High Tide | 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 | 3:58AM1.71m | 5:54PM1.79m | 4:53AM1.82m | 6:28PM1.85m | ||||||||
Low Tide | 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 | 10:58AM0.04m | 11:23PM0.92m | 11:43AM-0.03m | 00:02AM0.79m | ||||||||
5:20 | — | — | 5:20 | — | — | 5:20 | — | — | 5:22 | — | — | 5:22 | — | — | 5:22 | — | — | 5:24 | — | — | |
— | 7:00 | — | — | 7:00 | — | — | 6:59 | — | — | 6:58 | — | — | 6:57 | — | — | 6:55 | — | — | 6:54 | — | |
mm | — | — | 1 | 4 | 2 | 11 | 2 | — | 1 | — | — | — | — | — | — | — | — | — | — | 1 | — |
Temp °C | 33 | 32 | 28 | 30 | 30 | 27 | 30 | 30 | 26 | 29 | 29 | 26 | 29 | 29 | 26 | 28 | 28 | 26 | 28 | 28 | 26 |
Feels °C | 32 | 31 | 30 | 31 | 31 | 30 | 31 | 31 | 30 | 31 | 30 | 29 | 29 | 30 | 30 | 31 | 31 | 30 | 32 | 31 | 31 |
Swell 1 Height (m) Direction Period (s) | SE 14 | SE 15 | SE 14 | SE 13 | SE 12 | S 12 | SSW 12 | SSW 12 | SSW 12 | SSW 13 | SSW 13 | S 12 | SSW 12 | SSW 12 | S 11 | SSW 12 | SSW 11 | SSW 11 | SSW 11 | SSW 11 | SSW 10 |
10174 | 12237 | 9596 | 6277 | 4493 | 2096 | 2221 | 1759 | 1200 | 1100 | 760 | 1066 | 504 | 920 | 632 | 805 | 681 | 615 | 431 | 238 | 279 | |
Swell 2 Height (m) Direction Period (s) | — | — | — | E 16 | E 15 | E 15 | E 15 | E 15 | ESE 10 | E 13 | E 13 | E 13 | SSE 11 | E 12 | SW 12 | E 11 | E 11 | E 11 | E 10 | S 11 | E 10 |
— | — | — | 20 | 18 | 4 | 4 | 4 | 133 | 506 | 653 | 581 | 392 | 347 | 336 | 152 | 114 | 81 | 51 | 182 | 65 | |
Swell 3 Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | E 16 | S 11 | S 12 | SE 15 | E 13 | S 12 | E 12 | SE 13 | SE 13 | SE 13 | S 11 | E 10 | ESE 12 |
— | — | — | — | — | — | — | — | 44 | 155 | 322 | 9 | 451 | 93 | 221 | 28 | 27 | 27 | 38 | 71 | 30 | |
Wind waves Height (m) Direction Period (s) | — | — | SE 14 | E 10 | E 10 | ESE 10 | ESE 9 | ESE 9 | SE 8 | SE 7 | SE 7 | — | — | — | — | — | — | — | — | — | — |
— | — | 10352 | 1124 | 767 | 1203 | 929 | 826 | 428 | 189 | 121 | — | — | — | — | — | — | — | — | — | — | |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 77 | 531 | 0 | 531 | 531 | 0 | 425 | 515 | 0 | 0 | 20 | 0 | 20 | 20 | 0 | 9 | 42 | 9 | 9 | 42 | 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.











