Surf Forecasts:
Monabe Rivermouth surf forecast from 20 Jul 2026:
- Best quality surf: Sunday 26 Jul, 9AM (local time) - 2.5ft (0.7m), 11s period, S swell with glassy winds.
- Most powerful swell: Tuesday 28 Jul, 3AM (local time) - 5ft (1.6m), 11s period, S swell with 630 kJ wave energy.
- Next surfable swell (1★+): Sunday 26 Jul, 9AM (local time) - 2.5ft (0.7m), 11s period with S 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 (Jul 26) at 9AM. The primary swell is predicted to be 0.7m and 11s period with a secondary swell of 0.5m and 10s. Another secondary swell of 0.4m and 4s is also forecast. 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 1.6m 11s and forecast to arrive on Tuesday (Jul 28) at 3AM. Winds are predicted to be glassy at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.6m 14s period and expected on Tuesday (Jul 28) at 3AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 9AM (Sun 26th Jul) | 2.5ft (0.7m) 11s |
| Best Surf | 9AM (Sun 26th Jul) | 2.5ft (0.7m) 11s |
| Most Powerful | 3AM (Tue 28th Jul) | 5ft (1.6m) 11s |
Table - best surf conditions forecast for Monabe Rivermouth over the next 16 days.
The Lowdown
Alright, let’s see what’s brewing for the next couple of weeks.
I’ll level with you – this is a tough period. The only spot that’s even in the conversation is Monabe Rivermouth (Japan). It’s a rare breaker, so it doesn’t turn on often, and this forecast is a real rollercoaster. The first few days are tiny, with knee-high slop and the wind all wrong. Not worth paddling out for.
Things start to get a pulse around Sunday, July 26th. We’ve got a small south swell, just over 2 feet, but the morning is glassy and the energy is moderate (256). Still, it’s just rideable, nothing to get excited about. Monday the 27th is similar, with about 3 feet of south swell and glassy conditions in the morning, but the afternoon goes onshore and messy.
The big moment is Tuesday, July 28th. That morning, the swell jumps to around 8 feet from the south, with a period of 12 seconds. The energy is hammering – 2161, which is strong. And the wind? Dead flat, glassy. That’s a recipe for some serious waves. But here’s the thing: 8 feet is expert territory, and this is a rivermouth, so with that long period, it’ll be powerful and might break a bit straight. It’s for the brave only. Crowds are possible, so get there early.
After that, it gets messy again. The morning of the 29th is cross-onshore, and the swell drops. The 30th and 31st are back to small and poor. Then on August 1st, we see another pulse of about 7 feet from the ESE, but the wind is cross-shore, and it gets chopped out by the afternoon. August 2nd brings a bigger 12-foot swell from the SE, but again, onshore winds ruin it. That’s big, strong energy (2582), but it’s a messy, dangerous beast. Only for experts, and even then, the wind will make it a fight.
The last few days, from August 3rd to 5th, the swell drops back to 4 to 7 feet, with occasional glassy mornings but mostly onshore afternoons. The water temp is about average for the time of year.
So, bottom line: if you’re an expert, the early morning of Tuesday, July 28th is your window. That’s the one true standout. Everything else is a long shot. This spot doesn’t fire often, and a blank run is pretty normal here. Forecasts can change, but for now, keep your hopes in check.
Rusty.
Short Range ForecastMostly dry. Warm (max 30°C on Tue morning, min 26°C on Tue night). Wind will be generally light. | Days 5-7 Weather SummaryModerate rain (total 11mm), heaviest on Sun afternoon. Warm (max 30°C on Fri morning, min 26°C on Fri night). Wind will be generally light. | ||||||||||||||||||
Tuesday 21 | Wednesday 22 | Thursday 23 | Friday 24 | Saturday 25 | Sunday 26 | ||||||||||||||
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) | E 9 | E 11 | ESE 11 | ESE 10 | E 10 | E 10 | E 10 | E 10 | SE 10 | E 10 | SE 18 | SE 18 | SE 16 | SE 16 | SE 16 | SE 16 | S 11 | S 10 | S 10 |
Wave Graph  | |||||||||||||||||||
 kJ | 60 | 58 | 37 | 21 | 32 | 18 | 18 | 18 | 18 | 17 | 49 | 49 | 42 | 91 | 90 | 87 | 125 | 167 | 148 |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | glassy | glassy | on | glassy | cross-on | on | glassy | cross-on | on | glassy | glassy | on | cross-off | glassy | on | cross-off | glassy | on | cross-off |
High Tide | 10:14PM1.63m | 10:51AM1.37m | 10:46PM1.56m | 12:17PM1.26m | 11:25PM1.51m | 2:21PM1.26m | 00:20AM1.46m | 4:03PM1.34m | 1:37AM1.44m | 4:53PM1.44m | 2:50AM1.47m | 5:27PM1.53m | |||||||
Low Tide | 4:44AM0.67m | 4:25PM0.85m | 5:45AM0.66m | 5:07PM1.03m | 6:59AM0.64m | 6:19PM1.16m | 8:17AM0.59m | 8:22PM1.21m | 9:22AM0.50m | 9:48PM1.18m | 10:13AM0.41m | 10:39PM1.11m | |||||||
 |  | | | | | | | | | | |  | |  | |  | | | |
 | — | 5:09 | — | — | 5:09 | — | — | 5:09 | — | — | 5:11 | — | — | 5:11 | — | — | 5:11 | — | — |
 | 7:13 | — | 7:13 | — | — | 7:12 | — | — | 7:10 | — | — | 7:10 | — | — | 7:09 | — | — | 7:09 | — |
mm | — | — | — | — | — | — | — | — | — | — | — | — | 1 | — | 3 | 1 | 1 | 5 | 1 |
Temp °C | 28 | 30 | 30 | 27 | 30 | 29 | 27 | 30 | 30 | 27 | 30 | 30 | 27 | 30 | 30 | 27 | 29 | 30 | 27 |
Feels °C | 33 | 34 | 35 | 33 | 34 | 33 | 33 | 35 | 34 | 33 | 35 | 34 | 33 | 34 | 34 | 32 | 33 | 34 | 31 |
Swell 1 Height (m) Direction Period (s) | E 9 | E 11 | ESE 11 | E 8 | E 10 | E 10 | E 10 | SSW 4 | SE 10 | SW 4 | SSW 4 | SE 18 | SE 11 | SE 11 | SE 10 | SE 10 | S 11 | S 10 | S 10 |
| kJ | 60 | 58 | 37 | 12 | 32 | 18 | 18 | 3 | 15 | 4 | 3 | 49 | 42 | 41 | 37 | 49 | 125 | 167 | 148 |
Swell 2 Height (m) Direction Period (s) | SSW 7 | SSE 8 | E 8 | ESE 10 | ESE 10 | ESE 11 | SW 4 | E 10 | E 10 | E 10 | SE 10 | SE 9 | SE 16 | SE 16 | SE 16 | SE 16 | SE 10 | SE 11 | SE 11 |
| kJ | 5 | 7 | 21 | 21 | 11 | 11 | 2 | 18 | 18 | 17 | 14 | 14 | 42 | 91 | 90 | 87 | 50 | 55 | 56 |
Swell 3 Height (m) Direction Period (s) | SSE 8 | SSW 8 | SSE 8 | ENE 11 | SSE 8 | SSE 8 | ESE 10 | SE 9 | SE 19 | SE 10 | SE 18 | E 9 | E 9 | SSW 8 | S 8 | S 8 | SE 15 | SE 15 | SE 14 |
| kJ | 7 | 6 | 6 | 12 | 6 | 6 | 10 | 14 | 15 | 16 | 49 | 15 | 15 | 11 | 5 | 10 | 78 | 76 | 74 |
Wind waves Height (m) Direction Period (s) | SW 4 | SW 8 | SSW 8 | SW 3 | SSW 3 | SSW 3 | — | SW 4 | SSW 4 | — | — | SSW 4 | SW 4 | SSW 3 | SW 3 | SW 4 | SW 4 | SW 3 | SW 4 |
| kJ | 3 | 9 | 6 | 1 | 1 | 1 | — | 5 | 3 | — | — | 1 | 2 | 1 | 1 | 3 | 3 | 2 | 2 |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 9 | 9 | 910 | 42 | 42 | 302 | 235 | 47 | 490 | 42 | 9 | 42 | 9 | 9 | 42 | 9 | 0 | 47 | 0 |
Best forecast wave conditions in Shikoku | |||||||||||||||||||
Best forecast wave conditions in Japan | |||||||||||||||||||
Header Global | |||||||||||||||||||
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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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