Surf Forecasts:
Kugenuma Rivermouth surf forecast from 12 Aug 2026:
- Best quality surf: Saturday 15 Aug, 12AM (local time) - 1ft (0.3m), 12s period, S swell with cross-offshore winds.
- Most powerful swell: Saturday 15 Aug, 6AM (local time) - 1.5ft (0.5m), 12s period, S swell with 70 kJ wave energy.
- Next surfable swell (1★+): Saturday 15 Aug, 12AM (local time) - 1ft (0.3m), 12s period with S 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 12AM. The primary swell is predicted to be 0.3m and 12s period with a secondary swell of 0.3m and 9s. Another secondary swell of 0.3m and 5s is also forecast. Another secondary swell of 0.6m and 5s 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 0.5m 12s and forecast to arrive on Saturday (Aug 15) at 6AM. 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 Sunday (Aug 16) at 3AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 12AM (Sat 15th Aug) | 1ft (0.3m) 12s |
| Best Surf | 12AM (Sat 15th Aug) | 1ft (0.3m) 12s |
| Most Powerful | 6AM (Sat 15th Aug) | 1.5ft (0.5m) 12s |
Table - best surf conditions forecast for Kugenuma Rivermouth over the next 16 days.
The Lowdown
Alright, folks, Rusty here. Let’s cut to the chase: the next couple of weeks are looking pretty grim for surf. There’s a whole lot of nothing on the cards, so don’t go getting your hopes up too early.
We’ve got a real dry spell to start. There is simply no decent surf on offer for at least the first week. The first possible chance doesn't even roll in until around the 27th, which is over a week away. If you’re hanging for a wave, you’ll have to be patient. It happens sometimes, no point fighting it.
The only spot that gets a mention is Kugenuma Rivermouth. It’s a river break that does break fairly consistently, but it needs south swell. And right now, there’s nothing. For the first week, we're talking tiny, ankle-snapping waves, maybe 0.5ft to 2ft at best, with no power behind them. The winds are mostly light and variable, with a few clean, glassy mornings, but with that lack of swell, it’s just not worth the effort. You'd be better off taking a nap.
The water temp is about 81°F, which is pretty average for this time of year.
Then on August 27th, we finally see something. The swell pushes up to about 4ft out of the SSE, with a period of 10 seconds, and the energy jumps to a moderate 257. That’s much better. But here’s the catch – the wind is going to be right onshore from the south at around 19 mph, putting a messy chop on the surface. It will be surfable for sure, but far from perfect. This is the one to keep an eye on, but the wind has to play nice for it to be any good.
That’s the whole story. A whole lot of waiting, a few flat days, and one possible window of waves. Hope for the wind to ease off on the 27th.
Rusty, out.
Short Range ForecastHeavy rain (total 39mm), heaviest during Fri night. Warm (max 29°C on Thu afternoon, min 24°C on Wed night). Wind will be generally light. | Days 5-7 Weather SummaryMostly dry. Warm (max 29°C on Sat afternoon, min 23°C on Sun night). Wind will be generally light. | |||||||||||||||||||
Wed 12 | Thursday 13 | Friday 14 | Saturday 15 | Sunday 16 | Monday 17 | Tuesday 18 | ||||||||||||||
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) | SSW 10 | SSW 10 | S 10 | SSW 10 | SSW 9 | SSW 9 | SSW 9 | S 12 | S 11 | S 10 | SSW 9 | SSW 9 | SSW 9 | SE 10 | SSW 9 | SSW 9 | SSW 8 | SSW 8 | E 9 | SSE 10 |
Wave Graph  | ||||||||||||||||||||
 kJ | 59 | 39 | 50 | 31 | 28 | 16 | 28 | 25 | 63 | 54 | 29 | 29 | 29 | 28 | 28 | 16 | 14 | 14 | 13 | 10 |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross | off | off | glassy | off | off | cross-off | cross-off | cross-off | cross-off | off | off | cross-off | off | cross-off | cross-on | cross-on | cross-on | on | on |
High Tide | 5:45PM1.45m | 4:21AM1.49m | 5:58PM1.47m | 5:02AM1.53m | 6:14PM1.49m | 5:42AM1.54m | 6:33PM1.51m | 6:22AM1.51m | 6:54PM1.54m | 7:05AM1.44m | 7:19PM1.55m | 7:52AM1.34m | 7:45PM1.54m | |||||||
Low Tide | 11:02PM0.93m | 11:16AM0.20m | 11:27PM0.82m | 11:43AM0.25m | 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 | |||||||
 |  | | | | | | |  |  |  |  | |  | | | | | | | |
 | — | — | 4:58 | — | — | 5:00 | — | — | 5:00 | — | — | 5:01 | — | — | 5:01 | — | — | 5:03 | — | — |
 | 6:35 | — | — | 6:34 | — | — | 6:32 | — | — | 6:31 | — | — | 6:30 | — | — | 6:29 | — | — | 6:28 | — |
mm | 6 | 3 | 1 | 3 | 7 | 2 | 2 | 14 | 1 | — | — | — | — | — | — | — | — | — | — | — |
Temp °C | 27 | 25 | 27 | 29 | 27 | 28 | 29 | 26 | 28 | 29 | 26 | 27 | 28 | 25 | 27 | 27 | 25 | 26 | 26 | 26 |
Feels °C | 29 | 26 | 28 | 32 | 30 | 29 | 32 | 29 | 29 | 29 | 26 | 26 | 27 | 26 | 29 | 28 | 26 | 27 | 26 | 27 |
Swell 1 Height (m) Direction Period (s) | SSW 10 | SSW 10 | S 10 | SSW 10 | SSW 9 | SSW 9 | SSW 9 | SSW 9 | S 11 | S 10 | SSW 9 | SSW 9 | SSW 9 | SSW 9 | SSW 9 | SSW 9 | SSW 8 | SSW 8 | SSW 8 | SSW 8 |
| kJ | 59 | 39 | 50 | 31 | 28 | 16 | 28 | 16 | 63 | 54 | 29 | 29 | 29 | 28 | 28 | 16 | 14 | 14 | 7 | 7 |
Swell 2 Height (m) Direction Period (s) | SSE 5 | SSE 5 | SE 11 | E 10 | SE 9 | SE 5 | SE 5 | SE 5 | SE 8 | SSE 8 | SE 8 | SSE 8 | ESE 10 | SE 10 | ESE 10 | SE 11 | SE 10 | SE 10 | SE 10 | SSE 10 |
| kJ | 10 | 7 | 5 | 2 | 12 | 4 | 4 | 3 | 23 | 27 | 20 | 6 | 20 | 26 | 10 | 5 | 4 | 4 | 4 | 10 |
Swell 3 Height (m) Direction Period (s) | SE 10 | SE 12 | — | SE 12 | S 12 | S 12 | SE 11 | S 12 | SSE 9 | ESE 10 | ESE 10 | ESE 10 | SSE 11 | SSE 11 | SSE 11 | ESE 10 | SE 7 | S 7 | E 9 | E 8 |
| kJ | 4 | 5 | — | 5 | 11 | 11 | 5 | 25 | 16 | 9 | 10 | 11 | 12 | 12 | 12 | 10 | 2 | 1 | 13 | 5 |
Wind waves Height (m) Direction Period (s) | SE 5 | — | NNE 2 | — | — | NNE 2 | — | SE 5 | — | — | — | NE 2 | — | — | — | — | SSE 3 | SE 5 | S 3 | SSW 3 |
| kJ | 32 | — | 1 | — | — | 1 | — | 16 | — | — | — | 1 | — | — | — | — | 1 | 1 | 2 | 7 |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 18 | 2 | 8 | 24 | 2 | 45 | 24 | 0 | 463 | 0 | 8 | 45 | 8 | 0 | 45 | 45 | 45 | 57 | 84 | 84 |
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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