Surf Forecasts:
Kugenuma Rivermouth surf forecast from 21 Aug 2026:
- Best quality surf: Monday 24 Aug, 6AM (local time) - 1.5ft (0.5m), 19s period, SSE swell with glassy winds.
- Most powerful swell: Monday 24 Aug, 6PM (local time) - 5.5ft (1.7m), 16s period, SSE swell with 1,393 kJ wave energy.
- Next surfable swell (1★+): Monday 24 Aug, 3AM (local time) - 2ft (0.6m), 13s 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 Monday (Aug 24) at 3AM. The primary swell is predicted to be 0.6m and 13s period with a secondary swell of 0.3m and 8s. 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 1.7m 16s and forecast to arrive on Monday (Aug 24) at 6PM. Winds are predicted to be onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.3m 2s period and expected on Friday (Aug 28) at 3AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 3AM (Mon 24th Aug) | 2ft (0.6m) 13s |
| Best Surf | 6AM (Mon 24th Aug) | 1.5ft (0.5m) 19s |
| Most Powerful | 6PM (Mon 24th Aug) | 5.5ft (1.7m) 16s |
Table - best surf conditions forecast for Kugenuma Rivermouth over the next 16 days.
The Lowdown
Alright, Rusty here, with a look at what Kugenuma Rivermouth has in store.
It’s a slow start and honestly, not a lot to get excited about for the next week or so. The first few days are pretty much a write-off with tiny, poor quality surf. We’ve got a bit of a wait before anything really shapes up.
For the first real glimmer of hope, you’re looking at Monday, August 24th. The morning brings a bit of a pulse with a 2ft swell from the SSE, but the real story is the period – 19 seconds! That’s proper long-period groundswell energy, and the combined energy is reading 620 (moderate). The wind is onshore from the S though, and the report says it’s marginal, so it won’t be perfect, but it’s the first sign of life.
Things get more interesting on Sunday, August 30th. The morning session is the standout of the whole forecast. We’ve got a clean 4ft SSE swell, period of 12 seconds, and a gentle cross-offshore breeze from the NE. The combined energy is 539 (moderate) and the forecast is calling for "very good surf conditions." The water temp is about average for this time of year. This is the one to pencil in.
The swell builds through Sunday afternoon but the wind swings onshore, making it messy. Into the following week, we get another promising window on Wednesday, September 3rd. The afternoon shows a 5ft SSE swell with a moderate offshore breeze from the NNE. The period is short at 7 seconds, but with clean conditions and "good surf conditions" expected, it’s worth a look.
Looking way out, Sunday, September 6th has another potential good morning. A 4ft S swell, 13-second period, and a clean cross-offshore breeze. It’s a long way off, so don’t bank on it just yet, but the signs are there.
Honestly, for a spot that’s fairly consistent, this is a lean run. The best bet is to keep an eye on that Sunday the 30th. Until then, the board stays in the car.
Rusty.
Short Range ForecastModerate rain (total 16mm), heaviest on Sat night. Warm (max 29°C on Sun afternoon, min 24°C on Sat night). Wind will be generally light. | Days 5-7 Weather SummaryLight rain (total 9mm), mostly falling on Thu afternoon. Warm (max 28°C on Tue morning, min 23°C on Thu afternoon). Winds decreasing (fresh winds from the S on Tue afternoon, calm by Thu afternoon). | ||||||||||||||||||
Saturday 22 | Sunday 23 | Monday 24 | Tuesday 25 | Wednesday 26 | Thursday 27 | ||||||||||||||
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 9 | SSW 9 | SSW 9 | SSW 9 | SSW 9 | SE 13 | SE 13 | SSE 19 | SSE 16 | SSE 14 | S 14 | S 14 | S 13 | SSW 12 | SSW 12 | SSW 12 | SSW 10 | SSW 5 | S 7 |
Wave Graph  | |||||||||||||||||||
 kJ | 35 | 32 | 32 | 31 | 25 | 27 | 82 | 295 | 697 | 966 | 861 | 1179 | 784 | 545 | 619 | 422 | 56 | 69 | 60 |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | on | glassy | on | off | cross-off | cross-on | on | on | on | on | on | on | on | on | on | on | on | cross-on | on |
High Tide | 9:20PM1.38m | 5:30PM1.29m | 10:31PM1.31m | 4:48PM1.36m | 00:49AM1.28m | 4:54PM1.41m | 2:21AM1.33m | 5:05PM1.44m | 3:19AM1.40m | 5:16PM1.46m | 4:04AM1.47m | 5:28PM1.47m | |||||||
Low Tide | 6:47AM0.47m | 7:34PM1.28m | 8:09AM0.39m | 9:21PM1.20m | 9:06AM0.32m | 9:56PM1.11m | 9:48AM0.27m | 10:20PM1.01m | 10:23AM0.25m | 10:42PM0.89m | 10:52AM0.27m | 11:05PM0.77m | |||||||
 |  |  |  |  | | |  | | | | | | |  |  |  |  |  | |
 | — | 5:05 | — | — | 5:05 | — | — | 5:07 | — | — | 5:07 | — | — | 5:09 | — | — | 5:09 | — | — |
 | 6:23 | — | 6:22 | — | — | 6:22 | — | — | 6:21 | — | — | 6:19 | — | — | 6:17 | — | — | 6:16 | — |
mm | — | — | 1 | 14 | 1 | — | — | — | — | — | — | — | — | — | — | — | 1 | 8 | 8 |
Temp °C | 27 | 28 | 28 | 27 | 27 | 29 | 26 | 27 | 27 | 27 | 28 | 28 | 27 | 27 | 27 | 26 | 25 | 24 | 24 |
Feels °C | 29 | 31 | 31 | 30 | 28 | 31 | 29 | 29 | 28 | 29 | 29 | 27 | 27 | 29 | 27 | 27 | 26 | 27 | 26 |
Swell 1 Height (m) Direction Period (s) | SSW 9 | SSW 9 | SSW 9 | SSW 9 | SSW 9 | SSW 8 | SE 13 | SSE 16 | SSE 16 | SSE 14 | S 14 | S 14 | S 13 | SSW 12 | SSE 9 | SSE 9 | SSW 10 | SSE 9 | S 7 |
| kJ | 35 | 32 | 32 | 31 | 25 | 14 | 82 | 229 | 697 | 966 | 861 | 1179 | 784 | 545 | 33 | 33 | 56 | 17 | 60 |
Swell 2 Height (m) Direction Period (s) | SE 10 | S 4 | SE 10 | SE 10 | SE 10 | SE 13 | SSW 8 | SSE 19 | SSE 18 | S 16 | S 18 | ESE 13 | E 13 | SSE 10 | E 12 | E 11 | SSE 8 | — | SSW 8 |
| kJ | 4 | 3 | 4 | 4 | 4 | 27 | 14 | 295 | 427 | 438 | 390 | 59 | 3 | 37 | 3 | 2 | 13 | — | 7 |
Swell 3 Height (m) Direction Period (s) | S 9 | SE 10 | SE 11 | SE 11 | SE 13 | SSE 4 | S 18 | SSE 12 | SW 9 | ESE 12 | ESE 14 | SW 10 | ESE 13 | E 12 | SE 15 | E 16 | SSE 10 | — | SSE 10 |
| kJ | 2 | 4 | 5 | 5 | 7 | 2 | 6 | 96 | 3 | 26 | 39 | 15 | 56 | 3 | 9 | 5 | 10 | — | 9 |
Wind waves Height (m) Direction Period (s) | SSW 4 | S 5 | S 5 | S 5 | — | SE 4 | — | — | SSW 8 | SW 10 | SW 10 | S 4 | SSW 4 | — | SSW 12 | SSW 12 | SSW 5 | SSW 5 | — |
| kJ | 8 | 10 | 7 | 7 | — | 3 | — | — | 6 | 59 | 45 | 13 | 9 | — | 619 | 422 | 38 | 69 | — |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 84 | 26 | 84 | 63 | 57 | 24 | 7 | 18 | 85 | 7 | 84 | 85 | 7 | 7 | 30 | 19 | 89 | 84 | 7 |
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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