Surf Forecasts:
Kugenuma Rivermouth surf forecast from 28 Aug 2026:
- Best quality surf: Friday 4 Sep, 9AM (local time) - 6.5ft (2.0m), 7s period, S swell with offshore winds.
- Most powerful swell: Friday 4 Sep, 9AM (local time) - 6.5ft (2.0m), 7s period, S swell with 431 kJ wave energy.
- Next surfable swell (1★+): Friday 4 Sep, 3AM (local time) - 5.5ft (1.7m), 7s 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 Friday (Sep 04) at 3AM. The primary swell is predicted to be 1.7m and 7s period with a secondary swell of 0.9m and 6s. Another secondary swell of 0.8m and 7s 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 2.0m 7s and forecast to arrive on Friday (Sep 04) at 9AM. Winds are predicted to be offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.7m 4s period and expected on Friday (Sep 04) at 6PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 3AM (Fri 4th Sep) | 5.5ft (1.7m) 7s |
| Best Surf | 9AM (Fri 4th Sep) | 6.5ft (2.0m) 7s |
| Most Powerful | 9AM (Fri 4th Sep) | 6.5ft (2.0m) 7s |
Table - best surf conditions forecast for Kugenuma Rivermouth over the next 16 days.
The Lowdown
G’day, Rusty here. Look, I’m gonna be straight with you – for the next few days, Kugenuma Rivermouth is a write-off. The surf is tiny, the energy is weak, and conditions are just poor. We’re looking at a gap from now until the 4th of September with nothing worth paddling out for. The water’s sitting at a warm 82°, which is a touch warmer than normal for this time of year – nice for a swim, but not for a wave.
Then, on the morning of Friday the 4th of September, things finally kick off. We get a solid 7 ft swell from the S, and while the period is a short 7 seconds, the energy is there (736). The wind is offshore from the NE at 9 mph, which will keep the surface clean. This is the first real chance for a surf, but that short period means it’ll be a bit lumpy and less organised – still, after days of nothing, you’ll take it. The afternoon swings onshore, so make the most of the morning.
The next standout is the morning of Monday the 7th of September. Now this is the pick of the bunch for the first week. The swell is a solid 4 ft from the S with a long 12-second period, giving it some real push and better shaped waves. The wind is glassy – absolute zero – so it’ll be like a mirror out there. The energy is moderate at 525. Get on it early, because the wind turns onshore in the afternoon and ruins it.
We hit a bit of a rough patch after that. The 8th and 9th of September see the swell jump up to 8 ft to 12 ft from the S, but it’s onshore wind and messy. The energy is very strong (3342 on the 9th afternoon), but with the wind and size, this is for experienced crew only. Even then, the conditions are marginal.
Now, if you can wait, the real gold is on the morning of Sunday the 13th of September. This is your long-range standout. A 8 ft swell from the SSE with a very long 14-second period – that’s proper groundswell. The energy is massive (2064). Wind is glassy from the ENE at just 3 mph. The forecast says it’s excellent for experienced surfers, and I’d agree – that size and period will produce some meaty, clean walls. Just be aware it’s a river mouth, so that long period might make it break a bit straight, but with glassy conditions, the shape should be there. Keep an eye on this one – it’s promising.
Rusty.
Short Range ForecastLight rain (total 3mm), mostly falling on Sat morning. Warm (max 26°C on Mon afternoon, min 22°C on Sat afternoon). Winds decreasing (fresh winds from the NNE on Sat afternoon, light winds from the NE by Sun afternoon). | Days 4-6 Weather SummaryMostly dry. Warm (max 29°C on Thu afternoon, min 26°C on Tue morning). Mainly fresh winds. | ||||||||||||||||||||
Saturday 29 | Sunday 30 | Monday 31 | Tuesday 1 | Wednesday 2 | Thursday 3 | Friday 4 | |||||||||||||||
AM | 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 7 | SSW 7 | SSW 8 | SSW 8 | SSW 8 | SSW 7 | SSE 10 | SSE 10 | SSW 9 | SSW 9 | SSW 9 | SSW 9 | SSW 8 | SSW 9 | SSW 9 | SSW 11 | S 10 | SSE 7 | S 7 | S 7 | SSW 9 |
Wave Graph  | |||||||||||||||||||||
 kJ | 18 | 18 | 12 | 11 | 11 | 11 | 9 | 9 | 15 | 15 | 16 | 16 | 24 | 29 | 49 | 90 | 186 | 68 | 431 | 261 | 144 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-off | off | off | off | off | off | off | off | off | off | on | on | cross-on | on | on | on | on | on | off | on | cross-off |
High Tide | 5:58PM1.52m | 6:00AM1.54m | 6:18PM1.55m | 6:40AM1.50m | 6:40PM1.58m | 7:22AM1.41m | 7:05PM1.57m | 8:12AM1.30m | 7:32PM1.55m | 9:15AM1.18m | 7:59PM1.49m | 11:18AM1.09m | 8:28PM1.42m | ||||||||
Low Tide | 11:43AM0.38m | 11:57PM0.54m | 12:07PM0.47m | 00:28AM0.45m | 12:30PM0.58m | 1:04AM0.40m | 12:53PM0.70m | 1:45AM0.39m | 1:14PM0.83m | 2:34AM0.42m | 1:27PM0.97m | 3:41AM0.47m | 12:52PM1.08m | ||||||||
 | |  |  | | | | |  | |  |  | | | | | | | |  |  | |
 | 5:11 | — | — | 5:11 | — | — | 5:11 | — | — | 5:13 | — | — | 5:13 | — | — | 5:15 | — | — | 5:15 | — | — |
 | — | 6:14 | — | — | 6:13 | — | — | 6:10 | — | — | 6:09 | — | — | 6:08 | — | — | 6:07 | — | — | 6:06 | — |
mm | 1 | 1 | — | — | — | — | 1 | — | — | — | — | — | — | — | — | — | — | — | 2 | 10 | 49 |
Temp °C | 24 | 22 | 22 | 24 | 25 | 24 | 24 | 26 | 26 | 27 | 28 | 27 | 27 | 28 | 27 | 28 | 29 | 28 | 25 | 25 | 21 |
Feels °C | 26 | 19 | 20 | 25 | 27 | 26 | 25 | 28 | 28 | 30 | 32 | 30 | 31 | 29 | 28 | 28 | 28 | 30 | 27 | 28 | 19 |
Swell 1 Height (m) Direction Period (s) | SSW 7 | SSW 7 | SSW 7 | SSW 8 | SSW 8 | SSW 7 | SSW 7 | SSW 8 | SSW 9 | SSW 9 | SSW 9 | SSW 9 | SSW 8 | SSW 9 | SSW 9 | SSW 11 | SW 12 | SSE 7 | SSW 10 | S 7 | SSW 9 |
| kJ | 18 | 18 | 11 | 11 | 11 | 11 | 5 | 6 | 15 | 15 | 16 | 16 | 24 | 29 | 49 | 90 | 38 | 68 | 231 | 261 | 144 |
Swell 2 Height (m) Direction Period (s) | SSE 11 | SSE 11 | SSE 10 | SSE 10 | SSE 10 | SSE 10 | SSE 10 | SSE 10 | SSE 9 | SE 9 | SE 10 | SE 10 | SE 10 | ESE 7 | SE 7 | SSE 6 | E 9 | SSW 11 | SSE 8 | SSW 10 | SE 12 |
| kJ | 11 | 12 | 10 | 10 | 10 | 10 | 9 | 9 | 9 | 3 | 4 | 4 | 4 | 5 | 16 | 27 | 16 | 66 | 74 | 71 | 5 |
Swell 3 Height (m) Direction Period (s) | — | SSW 8 | SSW 8 | E 6 | E 6 | — | E 14 | E 13 | — | E 12 | ESE 12 | ESE 11 | SE 7 | SE 9 | SE 9 | SW 12 | — | E 11 | — | S 12 | SSE 12 |
| kJ | — | 12 | 12 | 3 | 3 | — | 4 | 3 | — | 3 | 13 | 11 | 2 | 3 | 3 | 6 | — | 9 | — | 3 | 13 |
Wind waves Height (m) Direction Period (s) | — | NE 2 | NNE 3 | — | — | — | — | — | — | — | — | — | — | — | S 3 | — | S 10 | SSW 7 | S 7 | NW 3 | N 4 |
| kJ | — | 1 | 1 | — | — | — | — | — | — | — | — | — | — | — | 1 | — | 186 | 47 | 431 | 4 | 10 |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 57 | 61 | 82 | 61 | 82 | 63 | 63 | 61 | 30 | 24 | 24 | 30 | 63 | 85 | 7 | 7 | 85 | 7 | 0 | 7 | 137 |
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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