Surf Forecasts:
Kugenuma Rivermouth surf forecast from 11 Jul 2026:
- Best quality surf: Monday 13 Jul, 3AM (local time) - 3.5ft (1.0m), 14s period, SSW swell with glassy winds.
- Most powerful swell: Saturday 11 Jul, 9PM (local time) - 6ft (1.9m), 16s period, SSW swell with 1,896 kJ wave energy.
- Next surfable swell (1★+): Monday 13 Jul, 3AM (local time) - 3.5ft (1.0m), 14s period with SSW swell.
Best Forecast Surf Conditions for Kugenuma Rivermouth this week:
The surf forecast for Kugenuma Rivermouth over the next 16 days: The first swell (rated 1 star or higher) is forecast to arrive on Monday (Jul 13) at 3AM. The primary swell is predicted to be 1.0m and 14s period with a secondary swell of 0.5m and 4s. Another secondary swell of 0.7m and 5s is also forecast. The wind is predicted to be glassy as the swell arrives.
The most powerful waves expected at Kugenuma Rivermouth in the next 16 days are 1.9m 16s and forecast to arrive on Saturday (Jul 11) at 9PM. Winds are predicted to be onshore at the time the swell arrives.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 3AM (Mon 13th Jul) | 3.5ft (1.0m) 14s |
| Best Surf | 3AM (Mon 13th Jul) | 3.5ft (1.0m) 14s |
| Most Powerful | 9PM (Sat 11th Jul) | 6ft (1.9m) 16s |
Table - best surf conditions forecast for Kugenuma Rivermouth over the next 16 days.
Alright, this is Rusty. Let me break it down for you on the feet and inches side.
Looking at the next 16 days, I gotta level with you – it’s a tough stretch. The first real chance of catching anything comes Monday morning, July 13th. Before that? Nothing. It’s a solid two and a half days of flat, blown-out junk. Onshore winds and tiny lumps that aren’t worth the walk.
So, your one and only highlight is early on Monday the 13th at Kugenuma Rivermouth (Japan). Swell’s a small 3ft from the SSW, with a 13-second period – that’s a real groundswell, so it’s got a bit of push even at that size. Water temp is about 76°, nothing unusual for the season. The combined energy is low at 267, so don’t expect much power. But the wind goes glassy – a 5 mph easterly making the surface perfect. It’s a river mouth, so it can be fickle, but on a clean, small day like that, it’s playful for beginners. Crowds are “often,” so you won’t be alone.
That’s it. By Monday afternoon, the wind shifts onshore and the quality dies. The rest of the week and all of the second week is a long, flat, windy mess. There’s a couple of mornings around July 25th and 26th that look clean, but the waves are barely 2ft with no energy – that’s not surf, it’s just a ripple. Only Monday morning, July 13th, is worth your time. Everything else is a hard pass.
Keep the chin up. It’ll change.
Rusty.
Short Range ForecastLight rain (total 2mm), mostly falling on Sat night. Warm (max 27°C on Mon morning, min 24°C on Sat night). Winds decreasing (fresh winds from the S on Sat afternoon, calm by Sun night). | Days 5-7 Weather SummaryMostly dry. Warm (max 28°C on Fri morning, min 25°C on Tue night). Wind will be generally light. | ||||||||||||||||||||
Sat 11 | Sunday 12 | Monday 13 | Tuesday 14 | Wednesday 15 | Thursday 16 | Friday 17 | |||||||||||||||
PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | |
Swell Height Map |  |  |  |  |  |  |  |  | |||||||||||||
Wave Height (m) Direction Period (s) | SSW 17 | SSW 16 | SSW 16 | SSW 16 | SSW 14 | SSW 13 | SSW 12 | SSW 11 | SSW 11 | SSW 10 | SSW 10 | SSW 9 | S 9 | SSW 9 | SSW 9 | SSW 8 | SW 8 | SSE 8 | S 8 | SSE 8 | SSE 8 |
Wave Graph  | |||||||||||||||||||||
 kJ | 2296 | 1697 | 1493 | 1107 | 487 | 249 | 206 | 128 | 91 | 59 | 38 | 34 | 81 | 16 | 8 | 7 | 18 | 61 | 134 | 53 | 63 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | on | on | on | on | on | glassy | on | on | cross-on | on | on | cross-on | on | on | on | cross-on | on | cross-on | cross-on | off | cross-off |
High Tide | 5:09PM1.30m | 1:43AM1.37m | 5:36PM1.36m | 2:36AM1.41m | 5:58PM1.39m | 3:24AM1.45m | 6:17PM1.41m | 4:10AM1.48m | 6:36PM1.42m | 4:54AM1.49m | 6:56PM1.43m | 5:38AM1.49m | 7:19PM1.44m | 6:24AM1.45m | |||||||
Low Tide | 9:11PM1.17m | 9:46AM0.13m | 10:00PM1.16m | 10:23AM0.07m | 10:36PM1.12m | 10:57AM0.05m | 11:07PM1.06m | 11:29AM0.05m | 11:37PM0.98m | 12:00PM0.09m | 00:11AM0.90m | 12:31PM0.16m | 00:49AM0.81m | ||||||||
 |  |  | |  | | |  | | | |  | |  | | | | | | |  | |
 | — | — | 4:35 | — | — | 4:35 | — | — | 4:37 | — | — | 4:37 | — | — | 4:37 | — | — | 4:39 | — | — | 4:39 |
 | 6:59 | — | — | 6:58 | — | — | 6:58 | — | — | 6:58 | — | — | 6:57 | — | — | 6:57 | — | — | 6:55 | — | 6:55 |
mm | — | 2 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 3 |
Temp °C | 26 | 26 | 26 | 26 | 26 | 27 | 27 | 25 | 26 | 26 | 26 | 27 | 27 | 26 | 26 | 27 | 26 | 28 | 28 | 27 | 26 |
Feels °C | 25 | 26 | 28 | 27 | 29 | 31 | 29 | 27 | 29 | 28 | 28 | 29 | 28 | 28 | 29 | 28 | 27 | 29 | 29 | 30 | 30 |
Swell 1 Height (m) Direction Period (s) | SSW 17 | SSW 16 | SSW 16 | SSW 16 | SSW 14 | SSW 13 | SSW 12 | SSW 11 | SSW 11 | SSW 10 | SSW 10 | SSW 9 | SE 10 | SSW 9 | SSW 9 | SSW 8 | SE 10 | SSE 8 | SW 8 | SSE 8 | SE 13 |
| kJ | 2296 | 1697 | 1493 | 1107 | 487 | 249 | 206 | 128 | 91 | 59 | 38 | 34 | 4 | 16 | 7 | 7 | 14 | 61 | 10 | 53 | 7 |
Swell 2 Height (m) Direction Period (s) | — | — | SE 10 | SE 10 | SSE 10 | S 5 | SE 10 | SE 9 | SE 9 | SE 12 | SE 10 | SE 10 | SE 8 | SE 9 | ESE 9 | SE 10 | SSW 8 | SSW 8 | ESE 9 | SW 8 | SW 8 |
| kJ | — | — | 35 | 32 | 9 | 14 | 4 | 3 | 3 | 6 | 4 | 4 | 3 | 3 | 8 | 4 | 7 | 7 | 16 | 2 | 2 |
Swell 3 Height (m) Direction Period (s) | — | — | SE 14 | SE 13 | ESE 13 | SE 10 | SE 13 | SE 12 | SE 12 | S 15 | S 14 | S 14 | S 13 | S 13 | S 13 | SE 8 | SW 8 | E 10 | E 15 | E 9 | — |
| kJ | — | — | 7 | 7 | 17 | 4 | 6 | 6 | 6 | 4 | 4 | 4 | 4 | 3 | 3 | 3 | 18 | 8 | 4 | 1 | — |
Wind waves Height (m) Direction Period (s) | S 4 | SSW 4 | — | — | S 4 | — | — | — | — | — | S 3 | — | S 9 | S 4 | S 3 | S 3 | S 3 | — | S 8 | S 4 | SSE 8 |
| kJ | 17 | 22 | — | — | 8 | — | — | — | — | — | 1 | — | 81 | 7 | 3 | 5 | 1 | — | 134 | 10 | 63 |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 85 | 7 | 7 | 137 | 7 | 0 | 26 | 7 | 26 | 7 | 57 | 64 | 85 | 64 | 26 | 85 | 84 | 64 | 64 | 0 | 18 |
Best forecast wave conditions in Kanagawa | |||||||||||||||||||||
Best forecast wave conditions in Japan | |||||||||||||||||||||
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Information about the Kugenuma Rivermouth Surf forecast
The above surf forecast table for Kugenuma Rivermouth provides essential information for determining whether the surfing conditions will be good over the next 16 days. A general guide to surfing at Kugenuma Rivermouth can be found by selecting the local surf guide option on the grey menu. Our Kugenuma 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 (Kugenuma 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 Kugenuma 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.
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