Surf Forecasts:
Monabe Rivermouth surf forecast from 29 Aug 2026:
- Best quality surf: Sunday 6 Sep, 9AM (local time) - 13ft (4.0m), 10s period, E swell with cross-offshore winds.
- Most powerful swell: Sunday 6 Sep, 9AM (local time) - 13ft (4.0m), 10s period, E swell with 3,070 kJ wave energy.
- Next surfable swell (1★+): Tuesday 1 Sep, 9PM (local time) - 2.5ft (0.7m), 12s 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 Tuesday (Sep 01) at 9PM. The primary swell is predicted to be 0.7m and 12s period with a secondary swell of 1.0m and 7s. 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 4.0m 10s and forecast to arrive on Sunday (Sep 06) at 9AM. Winds are predicted to be cross-offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.4m 9s period and expected on Friday (Sep 04) at 3PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 9PM (Tue 1st Sep) | 2.5ft (0.7m) 12s |
| Best Surf | 9AM (Sun 6th Sep) | 13ft (4.0m) 10s |
| Most Powerful | 9AM (Sun 6th Sep) | 13ft (4.0m) 10s |
Table - best surf conditions forecast for Monabe Rivermouth over the next 16 days.
The Lowdown
Alright, Rusty here. Let's break down what's cooking at Monabe Rivermouth. This river mouth spot doesn't break often, so we need everything to line up.
First up, the water's sitting pretty normal for this time of year, nothing out of the ordinary.
The forecast starts on August 30th with a tiny 1ft swell and glassy conditions, but the surf is poor. August 31st is the same story, small and messy. On Tuesday, September 1st, there's a 2ft swell with a long period of 13 seconds from the east. The energy is weak (128), so it's not doing a thing.
We've got a few days of nothing special. The first hint of life is on the morning of Wednesday, September 2nd. It's only 4ft, with a short 8-second period, but it's glassy. The energy is moderate at 348, but the conditions are still just "very ordinary". Not worth paddling out for.
Thursday the 3rd and Friday the 4th are poor. Then we hit Saturday, September 5th. The morning looks good. A 10ft swell from the east, 8-second period, with light offshore wind. That's a big jump, and the combined swell energy is strong (1041). The call is "expect good surf conditions". This is the first real standout. Clean offshore wind, but at 10ft, this is one for the experienced crew.
Sunday, September 6th gets even bigger at 12ft, but the wind goes onshore and cross-shore, creating chop. The energy is very strong (2306 and 2510), but the conditions are marginal. This looks more like a kitesurfing day than a paddle surf day.
The swell drops through Monday the 7th and into Tuesday, September 8th. Tuesday morning is another standout. We've got a 8ft swell from the ESE, but the wind is dead calm, glassy. The energy is strong at 1111, and conditions should be good. It'll be clean, but at 8ft, it's still solid and for experienced surfers.
The absolute best of the outlook lands on Saturday, September 12th. The morning brings a 10ft swell from the south with a very long period of 16 seconds. That's pure groundswell, and the energy is massive at 6437. The wind is a clean cross-offshore breeze. This is a serious, powerful swell for expert surfers only. It's two weeks out, so it's promising but not locked in.
After that, it drops off. Sunday the 13th is ordinary, and Monday, September 14th morning has another big 12ft swell from the south with cleaner wind. The energy is very strong (3774) and it's described as "very good", so that could be a late standout, but it's far out.
So, the day to circle is Saturday, September 12th for the big, clean, long-period groundswell—experts only. Closer in, Saturday, September 5th morning and Tuesday, September 8th morning are your best bets. And when it's on, expect a crowd here.
Rusty.
Short Range ForecastLight rain (total 8mm), mostly falling on Sun night. Warm (max 30°C on Sun morning, min 25°C on Mon night). Wind will be generally light. | Days 4-6 Weather SummaryModerate rain (total 15mm), heaviest on Wed afternoon. Warm (max 29°C on Wed morning, min 25°C on Wed night). Wind will be generally light. | ||||||||||||||||||||
Sunday 30 | Monday 31 | Tuesday 1 | Wednesday 2 | Thursday 3 | Friday 4 | Saturday 5 | |||||||||||||||
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 10 | SE 10 | SE 10 | SE 10 | SE 10 | ESE 14 | E 13 | E 13 | E 12 | SSE 8 | SSE 8 | SSE 8 | SSE 8 | SSE 8 | ESE 8 | E 8 | ESE 8 | ESE 8 | ESE 9 | ESE 9 | E 9 |
Wave Graph  | |||||||||||||||||||||
 kJ | 28 | 28 | 17 | 17 | 24 | 40 | 92 | 117 | 137 | 211 | 270 | 217 | 163 | 130 | 58 | 140 | 101 | 137 | 111 | 88 | 1143 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | glassy | on | cross-off | cross-on | on | glassy | glassy | on | cross-off | glassy | on | glassy | glassy | glassy | glassy | glassy | on | off | glassy | glassy | cross-off |
High Tide | 7:19PM1.85m | 7:27AM1.82m | 7:43PM1.84m | 8:08AM1.74m | 8:08PM1.81m | 8:53AM1.62m | 8:36PM1.75m | 9:49AM1.48m | 9:09PM1.67m | 11:15AM1.35m | 9:51PM1.57m | 1:52PM1.33m | 11:11PM1.47m | ||||||||
Low Tide | 1:05PM0.28m | 1:22AM0.42m | 1:34PM0.40m | 1:56AM0.37m | 2:03PM0.55m | 2:34AM0.36m | 2:35PM0.72m | 3:19AM0.39m | 3:09PM0.91m | 4:17AM0.45m | 3:53PM1.10m | 5:43AM0.50m | 5:37PM1.25m | ||||||||
 |  |  | | |  | | | | | | |  | |  |  | | |  | |  | |
 | 5:35 | — | — | 5:37 | — | — | 5:37 | — | — | 5:37 | — | — | 5:39 | — | — | 5:39 | — | — | 5:39 | — | — |
 | — | 6:34 | — | — | 6:31 | — | — | 6:30 | — | — | 6:30 | — | — | 6:28 | — | — | 6:27 | — | — | 6:25 | — |
mm | — | 2 | 4 | 1 | — | — | — | — | 1 | 1 | 7 | 4 | — | — | — | — | 3 | — | 1 | 10 | 2 |
Temp °C | 30 | 29 | 27 | 29 | 29 | 27 | 29 | 29 | 26 | 29 | 29 | 26 | 28 | 29 | 27 | 29 | 29 | 26 | 28 | 28 | 26 |
Feels °C | 34 | 34 | 33 | 34 | 33 | 33 | 31 | 32 | 30 | 32 | 32 | 31 | 32 | 34 | 32 | 32 | 32 | 30 | 32 | 33 | 29 |
Swell 1 Height (m) Direction Period (s) | SSW 7 | SE 10 | SSW 7 | SSW 9 | SSW 9 | SSW 9 | S 8 | SSE 7 | SSE 8 | SSE 8 | E 11 | SSE 8 | SSE 8 | SSE 8 | SSW 10 | SSW 9 | SSW 9 | SSW 10 | SSW 11 | SSW 11 | SSE 16 |
| kJ | 94 | 28 | 69 | 99 | 99 | 79 | 89 | 86 | 120 | 211 | 123 | 217 | 163 | 130 | 250 | 254 | 268 | 352 | 291 | 218 | 487 |
Swell 2 Height (m) Direction Period (s) | SE 10 | E 11 | SE 10 | SE 10 | SE 10 | ESE 14 | E 13 | E 13 | E 12 | E 11 | SE 11 | E 11 | E 10 | E 10 | ESE 8 | E 10 | ESE 8 | ESE 8 | ESE 9 | ESE 9 | SSW 10 |
| kJ | 28 | 21 | 17 | 17 | 24 | 40 | 92 | 117 | 137 | 119 | 18 | 114 | 74 | 98 | 58 | 18 | 101 | 137 | 111 | 88 | 111 |
Swell 3 Height (m) Direction Period (s) | E 11 | SSW 10 | SW 9 | E 11 | E 11 | SE 10 | SE 9 | SE 9 | SSW 9 | SE 10 | S 14 | SE 10 | SW 14 | SSW 12 | E 10 | — | E 10 | E 10 | SE 16 | SE 15 | SE 15 |
| kJ | 22 | 10 | 13 | 9 | 9 | 15 | 14 | 14 | 16 | 15 | 4 | 17 | 51 | 90 | 45 | — | 18 | 8 | 10 | 59 | 8 |
Wind waves Height (m) Direction Period (s) | — | SSW 7 | — | SW 4 | — | — | — | E 5 | — | — | SSE 8 | — | — | — | ENE 3 | E 8 | SSE 8 | — | ENE 4 | NE 5 | E 9 |
| kJ | — | 94 | — | 3 | — | — | — | 1 | — | — | 270 | — | — | — | 3 | 140 | 68 | — | 26 | 23 | 1143 |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 9 | 42 | 9 | 9 | 42 | 9 | 9 | 531 | 0 | 0 | 638 | 0 | 0 | 0 | 9 | 9 | 77 | 9 | 9 | 9 | 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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