Surf Forecasts:
Kugenuma Rivermouth surf forecast from 19 Aug 2026:
- Best quality surf: Wednesday 26 Aug, 9AM (local time) - 15ft (4.5m), 13s period, SSE swell with cross-offshore winds.
- Most powerful swell: Wednesday 26 Aug, 12PM (local time) - 16ft (5.0m), 12s period, SSE swell with 6,937 kJ wave energy.
- Next surfable swell (1★+): Sunday 23 Aug, 12PM (local time) - 1.5ft (0.4m), 15s period with SSE 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 Sunday (Aug 23) at 12PM. The primary swell is predicted to be 0.4m and 15s period with a secondary swell of 0.3m and 9s. 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 5.0m 12s and forecast to arrive on Wednesday (Aug 26) at 12PM. Winds are predicted to be cross-shore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.3m 2s period and expected on Sunday (Aug 23) at 6AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 12PM (Sun 23rd Aug) | 1.5ft (0.4m) 15s |
| Best Surf | 9AM (Wed 26th Aug) | 15ft (4.5m) 13s |
| Most Powerful | 12PM (Wed 26th Aug) | 16ft (5.0m) 12s |
Table - best surf conditions forecast for Kugenuma Rivermouth over the next 16 days.
The Lowdown
Alright, Rusty here. Let's have a look at what's on the menu for the next couple of weeks.
First off, I gotta be straight with you – the next few days are looking pretty flat. We're talking about a real slow start with nothing worth paddling out for from Wednesday the 19th right through to the early part of the following week. The swell is tiny, the wind is mostly on it, and it's just a write-off.
Things finally start to whisper to life around Monday morning, the 24th of August. There's a pulse of energy coming through at Kugenuma Rivermouth, with a 3ft swell from the SSE, but it's got a long period of 15 seconds. The combined energy is a moderate 326, so there's some push behind it, but the wind is a light cross-onshore, so it's not going to be pristine. The water temp is sitting at 80°, which is pretty much bang on average for this time of year.
The real standout, the one I've got my eye on, is the morning of Saturday the 29th of August. We're looking at a solid 6ft swell from the south with a moderate period of 10 seconds, and the wind is going to be a moderate offshore from the NNE. That's clean, groomed conditions. The combined energy is a strong 736. This is the one to get excited about. The following afternoon on the 29th, the swell drops a touch to 6ft, but the wind shifts to a light cross-offshore from the ENE, and the energy is still a chunky 1091. That's also going to be a clean session, but the morning session is the pick.
Looking a bit further out, the morning of Tuesday the 1st of September is another big one to circle. The swell is pushing 8ft from the SSE, with a very long period of 15 seconds. The wind is a light cross-offshore from the NE, and the combined energy is a massive 2712. This is proper groundswell, and it's going to be a heavy, powerful wave. This is strictly for experienced surfers only – it's going to be big and the long period will make it dumpy.
Alright, that's the lay of the land. Keep an eye on that Saturday the 29th morning, that's your best bet for a fun, clean session. The 1st of September is for the big dogs only.
Rusty.
Short Range ForecastMostly dry. Warm (max 27°C on Thu morning, min 25°C on Wed night). Wind will be generally light. | Days 5-7 Weather SummaryLight rain (total 5mm), mostly falling on Sun night. Warm (max 29°C on Tue afternoon, min 24°C on Sat night). Wind will be generally light. | ||||||||||||||||||
Thursday 20 | Friday 21 | Saturday 22 | Sunday 23 | Monday 24 | Tuesday 25 | ||||||||||||||
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) | SSW 8 | SSE 6 | SSW 9 | S 10 | SSW 9 | S 9 | SSW 9 | SSW 9 | SSW 9 | SW 9 | SSE 17 | SSE 15 | SSE 16 | SSE 15 | SSE 17 | SSE 16 | SSE 14 | S 16 | S 15 |
Wave Graph  | |||||||||||||||||||
 kJ | 6 | 4 | 8 | 8 | 27 | 127 | 35 | 32 | 32 | 21 | 27 | 196 | 828 | 1139 | 758 | 1870 | 1241 | 3928 | 3592 |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | on | cross-on | on | on | on | on | on | on | on | cross-off | cross-off | cross | cross-off | cross-off | cross-on | on | glassy | cross-on | glassy |
High Tide | 10:09AM1.09m | 8:44PM1.45m | 9:20PM1.38m | 5:30PM1.29m | 10:31PM1.31m | 4:48PM1.36m | 00:49AM1.28m | 4:54PM1.41m | 2:21AM1.33m | 5:05PM1.44m | |||||||||
Low Tide | 3:29AM0.49m | 1:48PM0.98m | 4:58AM0.51m | 6:47AM0.47m | 7:34PM1.28m | 8:09AM0.39m | 9:21PM1.20m | 9:06AM0.32m | 9:56PM1.11m | 9:48AM0.27m | 10:20PM1.01m | ||||||||
 |  |  |  |  | | | | |  | | |  | | | | | | | |
 | — | 5:03 | — | — | 5:05 | — | — | 5:05 | — | — | 5:05 | — | — | 5:07 | — | — | 5:07 | — | — |
 | 6:27 | — | 6:25 | — | — | 6:23 | — | — | 6:22 | — | — | 6:22 | — | — | 6:21 | — | — | 6:19 | — |
mm | — | — | — | — | — | — | — | — | — | 3 | — | — | 2 | — | — | — | — | — | 6 |
Temp °C | 26 | 27 | 27 | 26 | 27 | 27 | 26 | 27 | 27 | 27 | 26 | 28 | 26 | 27 | 28 | 26 | 28 | 29 | 28 |
Feels °C | 28 | 29 | 29 | 28 | 28 | 27 | 26 | 29 | 29 | 32 | 29 | 31 | 29 | 30 | 31 | 29 | 31 | 32 | 32 |
Swell 1 Height (m) Direction Period (s) | SSE 6 | SSE 6 | SSW 9 | SSW 8 | SSW 9 | SE 11 | SSW 9 | SSW 9 | SSW 9 | S 5 | SSW 9 | SSE 15 | SSE 16 | SSE 15 | SSE 14 | SSE 16 | SSE 14 | S 16 | S 15 |
| kJ | 3 | 3 | 8 | 6 | 27 | 4 | 35 | 32 | 32 | 7 | 15 | 196 | 828 | 1139 | 630 | 1870 | 1241 | 3928 | 3592 |
Swell 2 Height (m) Direction Period (s) | SE 10 | SE 10 | SSE 6 | S 10 | SE 11 | S 9 | SE 10 | S 5 | SE 10 | SW 9 | SSE 17 | SSW 8 | SSW 8 | SSW 9 | SSE 17 | SW 10 | S 16 | ESE 13 | E 13 |
| kJ | 4 | 4 | 3 | 8 | 4 | 2 | 4 | 7 | 4 | 21 | 27 | 24 | 14 | 15 | 758 | 26 | 1222 | 35 | 30 |
Swell 3 Height (m) Direction Period (s) | SSW 8 | SW 8 | SE 11 | SE 11 | ESE 5 | S 13 | S 9 | SE 10 | SE 11 | SSE 10 | S 5 | SSE 4 | E 12 | ESE 12 | SSW 9 | ESE 15 | SW 10 | — | — |
| kJ | 6 | 2 | 4 | 4 | 3 | 3 | 2 | 4 | 5 | 10 | 2 | 2 | 27 | 27 | 7 | 42 | 4 | — | — |
Wind waves Height (m) Direction Period (s) | — | — | S 2 | SSW 3 | SSW 3 | S 9 | SSW 4 | — | S 3 | SW 3 | ENE 2 | — | — | — | — | — | — | — | — |
| kJ | — | — | 1 | 3 | 2 | 127 | 7 | — | 8 | 3 | 1 | — | — | — | — | — | — | — | — |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 84 | 85 | 84 | 84 | 84 | 85 | 84 | 26 | 84 | 45 | 45 | 18 | 0 | 0 | 26 | 7 | 0 | 879 | 0 |
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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