Surf Forecasts:
Kugenuma Rivermouth surf forecast from 14 Aug 2026:
- Best quality surf: Saturday 15 Aug, 9PM (local time) - 2.5ft (0.8m), 11s period, SE swell with cross-offshore winds.
- Most powerful swell: Saturday 15 Aug, 9PM (local time) - 2.5ft (0.8m), 11s period, SE swell with 134 kJ wave energy.
- Next surfable swell (1★+): Saturday 15 Aug, 6AM (local time) - 2.5ft (0.8m), 6s period with ESE 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 Saturday (Aug 15) at 6AM. The primary swell is predicted to be 0.8m and 6s period with a secondary swell of 0.5m and 5s. Another secondary swell of 0.4m and 11s is also forecast. The wind is predicted to be cross-offshore as the swell arrives.
The most powerful waves expected at Kugenuma Rivermouth in the next 16 days are 0.8m 11s and forecast to arrive on Saturday (Aug 15) at 9PM. Winds are predicted to be cross-offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.4m 3s period and expected on Wednesday (Aug 19) at 3AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 6AM (Sat 15th Aug) | 2.5ft (0.8m) 6s |
| Best Surf | 9PM (Sat 15th Aug) | 2.5ft (0.8m) 11s |
| Most Powerful | 9PM (Sat 15th Aug) | 2.5ft (0.8m) 11s |
Table - best surf conditions forecast for Kugenuma Rivermouth over the next 16 days.
The Lowdown
Alright folks, Rusty here. Let's get into it for Kugenuma Rivermouth. It's a quiet stretch ahead, so don't get your hopes up too high.
Right off the bat, we're looking at a long, flat spell. From now through to around the 23rd of August, there's just nothing doing. The swell is small, the wind is all wrong, and the scores are rock bottom. The water temp is sitting at about 81°, which is pretty much average for this time of year, so at least it'll be a nice swim.
The first real glimmer of hope shows up on the 24th of August. We get a pulse of long-period groundswell, 2ft from the SE with a period of 15 seconds. The combined energy jumps to a moderate 259, but the wind is a light cross-onshore, so the surface will be a bit bumpy. It is classified as marginal, so it's just a teaser, really.
Now, the standout window arrives on Tuesday the 25th of August. This is the one to circle. Morning sees a clean 3ft swell from the SE, 14-second period, with a moderate offshore wind from the N. That’s the kind of clean, lined-up look you want. But the afternoon is the real gem. The wind goes glassy, and the swell holds at 3ft from the SE, 14-second period, with the energy at a solid 277. That combination of glassy conditions and long-period groundswell is where the magic happens. It'll be a bit weak for the experts, but for beginners and longboarders, this is the pick of the bunch.
After that, Wednesday the 26th sees the swell size bump up to 4ft, but the wind swings onshore and kills the quality. The rest of the run is back to small, poor conditions with a variety of wind directions.
So, to sum it up: if you can only paddle out once, make it Tuesday afternoon, the 25th. The glassy surface and that long-period SE swell will make for the cleanest, most playful session of the whole outlook. Just be aware that with that long period, the Kugenuma Rivermouth might straighten out a bit on the bank, but with the offshore flow, it should still be fun.
Stay patient, and keep an eye on the forecasts.
Rusty.
Short Range ForecastHeavy rain (total 21mm), heaviest during Fri night. Warm (max 29°C on Sat afternoon, min 24°C on Sat night). Wind will be generally light. | Days 5-7 Weather SummaryLight rain (total 5mm), mostly falling on Tue afternoon. Warm (max 30°C on Wed morning, min 25°C on Mon night). Wind will be generally light. | ||||||||||||||||||
Saturday 15 | Sunday 16 | Monday 17 | Tuesday 18 | Wednesday 19 | Thursday 20 | ||||||||||||||
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) | SSE 10 | SSW 11 | ESE 10 | SSW 9 | SSW 9 | SE 9 | S 9 | SSW 9 | SSW 8 | SSW 8 | SE 6 | SE 7 | SE 7 | SE 7 | SE 7 | SSE 7 | S 8 | SSE 7 | SE 11 |
Wave Graph  | |||||||||||||||||||
 kJ | 20 | 40 | 120 | 28 | 28 | 50 | 37 | 15 | 14 | 13 | 6 | 8 | 10 | 13 | 11 | 17 | 33 | 18 | 33 |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-off | cross-off | cross-on | cross-off | cross-off | cross | cross-off | cross-off | cross-on | cross-off | off | cross-off | off | off | cross | cross-off | cross-off | cross | cross-off |
High Tide | 5:42AM1.54m | 6:33PM1.51m | 6:22AM1.51m | 6:54PM1.54m | 7:05AM1.44m | 7:19PM1.55m | 7:52AM1.34m | 7:45PM1.54m | 8:48AM1.21m | 8:14PM1.50m | 10:09AM1.09m | 8:44PM1.45m | |||||||
Low Tide | 11:54PM0.70m | 12:09PM0.32m | 00:25AM0.60m | 12:34PM0.42m | 1:01AM0.53m | 1:00PM0.55m | 1:41AM0.48m | 1:24PM0.69m | 2:29AM0.47m | 1:44PM0.84m | 3:29AM0.49m | 1:48PM0.98m | |||||||
 |  |  |  | |  |  | | | | | | |  | |  | | | | |
 | — | 5:00 | — | — | 5:01 | — | — | 5:01 | — | — | 5:03 | — | — | 5:03 | — | — | 5:03 | — | — |
 | 6:32 | — | 6:31 | — | — | 6:30 | — | — | 6:29 | — | — | 6:28 | — | — | 6:27 | — | — | 6:25 | — |
mm | 16 | 1 | — | — | — | — | 3 | 1 | — | 1 | — | 2 | 2 | — | — | — | — | — | 1 |
Temp °C | 27 | 28 | 29 | 26 | 27 | 28 | 26 | 27 | 28 | 26 | 29 | 29 | 27 | 30 | 30 | 27 | 29 | 29 | 27 |
Feels °C | 31 | 29 | 30 | 27 | 28 | 30 | 28 | 30 | 30 | 28 | 30 | 30 | 30 | 32 | 33 | 31 | 32 | 32 | 31 |
Swell 1 Height (m) Direction Period (s) | SSW 9 | SE 5 | SE 8 | SSE 8 | SSW 9 | S 9 | S 9 | SSW 9 | SSW 8 | SE 5 | SE 6 | SE 7 | SE 7 | SE 7 | SE 7 | SSE 7 | S 8 | SSE 7 | S 8 |
| kJ | 16 | 10 | 33 | 24 | 28 | 39 | 37 | 15 | 14 | 7 | 6 | 8 | 7 | 13 | 11 | 17 | 33 | 18 | 33 |
Swell 2 Height (m) Direction Period (s) | SSE 10 | SSW 11 | S 10 | SSW 9 | SE 7 | SSE 11 | SE 11 | SE 6 | SE 6 | SSW 8 | SSW 8 | SSW 8 | SSE 10 | SE 10 | SE 10 | S 9 | SE 10 | SSW 9 | ESE 11 |
| kJ | 20 | 40 | 52 | 28 | 14 | 12 | 19 | 5 | 5 | 13 | 6 | 6 | 10 | 4 | 4 | 7 | 4 | 16 | 11 |
Swell 3 Height (m) Direction Period (s) | S 12 | SSE 9 | SE 10 | SE 12 | SSE 12 | E 10 | E 8 | SSE 11 | SE 11 | SE 10 | SE 10 | SE 10 | SW 8 | SW 8 | SW 8 | SE 10 | ESE 9 | SE 10 | SE 11 |
| kJ | 11 | 16 | 4 | 6 | 14 | 2 | 1 | 11 | 5 | 4 | 4 | 4 | 2 | 3 | 3 | 4 | 15 | 4 | 29 |
Wind waves Height (m) Direction Period (s) | SE 4 | — | ESE 10 | — | — | SE 9 | — | — | — | — | — | — | — | NNE 3 | — | — | — | — | — |
| kJ | 5 | — | 120 | — | — | 50 | — | — | — | — | — | — | — | 3 | — | — | — | — | — |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 8 | 0 | 64 | 8 | 2 | 13 | 2 | 545 | 24 | 30 | 57 | 482 | 30 | 57 | 64 | 57 | 2 | 24 | 0 |
Best forecast wave conditions in Kanagawa | |||||||||||||||||||
Best forecast wave conditions in Japan | |||||||||||||||||||
Header Global | |||||||||||||||||||
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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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