Surf Forecasts:
Kugenuma Rivermouth surf forecast from 4 Sep 2026:
- Best quality surf: Tuesday 8 Sep, 6AM (local time) - 6ft (1.9m), 10s period, S swell with glassy winds.
- Most powerful swell: Tuesday 8 Sep, 12AM (local time) - 10ft (3.0m), 11s period, S swell with 2,241 kJ wave energy.
- Next surfable swell (1★+): Friday 4 Sep, 3PM (local time) - 2ft (0.6m), 10s 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 Friday (Sep 04) at 3PM. The primary swell is predicted to be 0.6m and 10s period with a secondary swell of 0.4m and 6s. The wind is predicted to be offshore as the swell arrives.
The most powerful waves expected at Kugenuma Rivermouth in the next 16 days are 3.0m 11s and forecast to arrive on Tuesday (Sep 08) at 12AM. Winds are predicted to be onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.1m 4s period and expected on Sunday (Sep 06) at 9PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 3PM (Fri 4th Sep) | 2ft (0.6m) 10s |
| Best Surf | 6AM (Tue 8th Sep) | 6ft (1.9m) 10s |
| Most Powerful | 12AM (Tue 8th Sep) | 10ft (3.0m) 11s |
Table - best surf conditions forecast for Kugenuma Rivermouth over the next 16 days.
The Lowdown
Alright folks, Rusty here. Let's talk about what's coming up for Kugenuma Rivermouth.
The next week and a half is pretty flat and sad, honestly. We’re looking at a big chunk of time with barely a ripple. Things don't really get going until Monday the 8th of September, so you can basically write off the next four or five days.
The Overall Pattern & The Best Window
Right now, it’s just small. Friday morning the 4th has a tiny 2ft south swell, but it’s clean with a light offshore. It's surfable, but nothing to get excited about. The weekend is a write-off. Saturday has a bit of a south-west swell, but it's tiny at 1ft, plus it's raining and blowing a fresh offshore at 19 mph. Sunday is even worse – a 0.7ft south-east swell with howling cross-offshore winds. The water’s warm at 80°, which is about average for this time of year.
That said, the real standout here is a solid pulse of south swell and clean wind. Monday the 8th of September is your best bet. The morning is looking great with 6ft of south swell at a 10-second period and a light NNE offshore breeze. The wave energy is strong (730), and it’s going to be clean. This is a decent groundswell, so with the long period, it should wrap in nicely at the rivermouth. It’s big enough to be fun for intermediates and above but might be a bit heavy for beginners. Tuesday the 9th morning is still good, with 4ft south swell and light offshore wind, offering a solid backup session, though the energy drops to moderate (324).
The Rest of the Run
After that, it’s back to the small stuff. By late in the second week, we see a little push of 3ft on Friday the 19th, but with a short period and a fresh offshore wind, it will be hard to paddle into and the quality isn't there.
Overall, there's one true standout session on Monday the 8th of September. Before that, it’s flat and frustrating. After that, the surf drops back down to tiny, messy waves. The river mouth can get a bit busy when it’s good, but for that Monday morning, it'll be worth paddling out for a session.
Stay hopeful.
- Rusty
Short Range ForecastHeavy rain (total 276mm), heaviest during Sun night. Warm (max 27°C on Fri afternoon, min 20°C on Sun morning). Winds increasing (light winds from the NE on Fri morning, strong winds from the N by Sun afternoon). | Days 4-6 Weather SummaryHeavy rain (total 66mm), heaviest during Wed night. Warm (max 26°C on Mon afternoon, min 21°C on Wed night). Wind will be generally light. | ||||||||||||||||||||
Friday 4 | Saturday 5 | Sunday 6 | Monday 7 | Tuesday 8 | Wednesday 9 | Thursday 10 | |||||||||||||||
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) | S 10 | S 10 | SSW 9 | SSW 9 | SSW 9 | SSW 8 | SSE 8 | SSE 8 | SSE 12 | SSE 11 | SSE 10 | S 11 | S 10 | S 10 | S 11 | S 10 | S 9 | S 9 | S 8 | S 8 | S 8 |
Wave Graph  | |||||||||||||||||||||
 kJ | 73 | 70 | 68 | 35 | 27 | 14 | 7 | 23 | 349 | 611 | 734 | 2241 | 596 | 669 | 649 | 318 | 201 | 129 | 49 | 49 | 33 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | off | off | off | off | off | off | off | cross-off | cross-off | on | on | on | off | off | off | off | off | off | off | off | off |
High Tide | 11:18AM1.09m | 8:28PM1.42m | 9:04PM1.32m | 4:27PM1.34m | 11:39PM1.24m | 4:24PM1.40m | 1:50AM1.27m | 4:34PM1.43m | 2:58AM1.36m | 4:45PM1.45m | 3:46AM1.44m | 4:57PM1.47m | |||||||||
Low Tide | 12:52PM1.08m | 5:26AM0.51m | 7:15AM0.47m | 9:04PM1.21m | 8:27AM0.40m | 9:35PM1.10m | 9:17AM0.35m | 9:58PM0.98m | 9:55AM0.33m | 10:20PM0.85m | 10:27AM0.35m | 10:42PM0.73m | |||||||||
 | |  |  |  |  | | | | |  |  |  |  |  | | | | | | | |
 | 5:15 | — | — | 5:16 | — | — | 5:16 | — | — | 5:18 | — | — | 5:18 | — | — | 5:18 | — | — | 5:20 | — | — |
 | — | 6:06 | — | — | 6:04 | — | — | 6:02 | — | — | 6:01 | — | — | 6:00 | — | — | 5:59 | — | — | 5:57 | — |
mm | — | — | 29 | 18 | 1 | 1 | 5 | 20 | 202 | 5 | 1 | 7 | 1 | 9 | 10 | 2 | 4 | 27 | 11 | 6 | 2 |
Temp °C | 26 | 27 | 24 | 21 | 21 | 21 | 20 | 20 | 23 | 23 | 26 | 26 | 26 | 23 | 22 | 24 | 23 | 23 | 21 | 20 | 20 |
Feels °C | 27 | 28 | 24 | 19 | 19 | 18 | 15 | 14 | 24 | 26 | 29 | 28 | 29 | 23 | 21 | 27 | 25 | 23 | 20 | 18 | 19 |
Swell 1 Height (m) Direction Period (s) | S 10 | S 10 | SSW 9 | SSW 9 | SSW 9 | SSW 8 | SSE 8 | SSE 8 | SSE 12 | SSE 11 | SSE 10 | S 11 | S 10 | S 10 | S 11 | S 10 | S 9 | S 9 | S 8 | S 8 | S 8 |
| kJ | 73 | 70 | 68 | 35 | 27 | 14 | 7 | 23 | 349 | 611 | 734 | 970 | 596 | 669 | 649 | 318 | 201 | 129 | 49 | 49 | 33 |
Swell 2 Height (m) Direction Period (s) | SE 7 | SE 6 | SSE 6 | SE 9 | ESE 7 | SE 8 | S 8 | S 8 | SE 11 | ESE 9 | S 11 | SE 14 | SSW 11 | SSW 11 | E 18 | E 12 | E 16 | SSW 9 | SSW 9 | — | SE 9 |
| kJ | 7 | 10 | 4 | 12 | 4 | 11 | 5 | 1 | 5 | 300 | 38 | 47 | 128 | 319 | 6 | 3 | 5 | 119 | 27 | — | 3 |
Swell 3 Height (m) Direction Period (s) | SE 9 | SE 9 | SE 9 | SE 9 | SE 8 | SW 10 | SW 9 | SW 9 | E 8 | ESE 11 | E 9 | — | E 8 | — | — | E 12 | E 9 | ESE 9 | E 11 | SE 10 | E 7 |
| kJ | 3 | 3 | 3 | 12 | 3 | 4 | 3 | 3 | 173 | 12 | 40 | — | 6 | — | — | 3 | 2 | 9 | 2 | 17 | 1 |
Wind waves Height (m) Direction Period (s) | — | — | NNE 2 | NNE 3 | NNE 3 | NNE 3 | NNE 4 | NNE 4 | N 4 | N 4 | — | S 11 | — | NE 3 | NE 3 | NE 3 | NNE 2 | — | NE 2 | ENE 2 | ENE 2 |
| kJ | — | — | 1 | 7 | 4 | 5 | 17 | 20 | 45 | 10 | — | 2241 | — | 5 | 2 | 2 | 1 | — | 1 | 1 | 1 |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 0 | 0 | 0 | 57 | 503 | 480 | 480 | 545 | 559 | 7 | 7 | 222 | 0 | 18 | 0 | 0 | 0 | 140 | 0 | 545 | 45 |
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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