Surf Forecasts:
Kugenuma Rivermouth surf forecast from 12 Jul 2026:
- Best quality surf: Monday 13 Jul, 3AM (local time) - 3.5ft (1.0m), 14s period, SSW swell with glassy winds.
- Most powerful swell: Sunday 12 Jul, 9PM (local time) - 4.5ft (1.3m), 15s period, SSW swell with 656 kJ wave energy.
- Next surfable swell (1★+): Monday 13 Jul, 3AM (local time) - 3.5ft (1.0m), 14s period with SSW 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 (Jul 13) at 3AM. The primary swell is predicted to be 1.0m and 14s period with a secondary swell of 0.5m and 5s. 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 1.3m 15s and forecast to arrive on Sunday (Jul 12) at 9PM. Winds are predicted to be cross-onshore at the time the swell arrives.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 3AM (Mon 13th Jul) | 3.5ft (1.0m) 14s |
| Best Surf | 3AM (Mon 13th Jul) | 3.5ft (1.0m) 14s |
| Most Powerful | 9PM (Sun 12th Jul) | 4.5ft (1.3m) 15s |
Table - best surf conditions forecast for Kugenuma Rivermouth over the next 16 days.
Alright, let’s get into this. The forecast for Kugenuma Rivermouth is pretty grim for the next 16 days. We start on Sunday, July 12th, but right off the bat, there’s a big gap of poor surf. The first entry shows a 5-foot swell from the SSW, but the wind is onshore from the south at 9 mph, and the energy is moderate (1146). The wave comment says conditions are marginal. The water is at 76°, which is about normal for this time of year.
The only real window is Monday morning, July 13th. You’ll want to get out early. The swell drops to 3 feet from the SSW, but the wind goes glassy. That’s a huge plus. The period is 13 seconds, a groundswell, which will give the waves some shape, but the energy is still moderate (313). The morning is the only time we see “good surf conditions” in the data. It’s a beginner-friendly spot, so it’s worth a look.
After that, it’s a long dry spell. From Tuesday, July 14th, all the way through to Monday, July 27th, the surf is consistently poor. The swell becomes tiny, mostly knee-high at 1 to 2 feet, with onshore winds from the south or SSW. The energy levels are weak, often under 100, and the wind stays messy. There are a few moments of clean cross-offshore winds on the 19th, 20th, and 21st, but the swell is just too small to get excited about—2 to 2 feet tops. It’s flat.
The last week of July is a bust. The swells are barely 1 foot, with energy in the 20s and 30s. The wind is occasionally glassy on the 25th, but with 1-foot waves, it’s not going to break. The 27th shows a 1-foot swell with a 14-second period, but the wind is cross-onshore, so don’t bother.
The 16-day window is a tough one. The only real moment is the Monday morning glass-off. If you’re keen, that’s your best bet. Otherwise, it’s a barren stretch. For a rivermouth setup, this kind of blank run is normal when the swell direction and wind don’t line up. Keep an eye on things, but for now, I’d say take a break.
Rusty
Short Range ForecastMostly dry. Warm (max 27°C on Mon morning, min 25°C on Mon night). Wind will be generally light. | Days 5-7 Weather SummaryLight rain (total 2mm), mostly falling on Thu night. Warm (max 28°C on Wed afternoon, min 25°C on Fri night). Winds decreasing (fresh winds from the S on Thu afternoon, light winds from the SE by Fri night). | ||||||||||||||||||||
Sun 12 | Monday 13 | Tuesday 14 | Wednesday 15 | Thursday 16 | Friday 17 | Saturday 18 | |||||||||||||||
PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | PM | Night | AM | |
Swell Height Map |  |  |  |  |  |  |  |  | |||||||||||||
Wave Height (m) Direction Period (s) | SSW 16 | SSW 14 | SSW 13 | SSW 12 | SSW 11 | SSW 11 | SSW 10 | SSW 10 | SSW 9 | S 9 | SSW 4 | SSW 5 | S 5 | S 5 | SE 17 | SE 15 | SE 13 | SE 13 | SE 12 | SE 11 | SE 10 |
Wave Graph  | |||||||||||||||||||||
 kJ | 1107 | 569 | 302 | 206 | 109 | 66 | 59 | 38 | 34 | 81 | 25 | 24 | 64 | 31 | 142 | 444 | 290 | 242 | 210 | 174 | 153 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | on | on | glassy | cross-on | glassy | on | on | on | on | on | on | on | on | on | on | on | cross-on | cross | on | glassy | cross-off |
High Tide | 5:36PM1.36m | 2:36AM1.41m | 5:58PM1.39m | 3:24AM1.45m | 6:17PM1.41m | 4:10AM1.48m | 6:36PM1.42m | 4:54AM1.49m | 6:56PM1.43m | 5:38AM1.49m | 7:19PM1.44m | 6:24AM1.45m | 7:45PM1.45m | 7:12AM1.37m | |||||||
Low Tide | 10:00PM1.16m | 10:23AM0.07m | 10:36PM1.12m | 10:57AM0.05m | 11:07PM1.06m | 11:29AM0.05m | 11:37PM0.98m | 12:00PM0.09m | 00:11AM0.90m | 12:31PM0.16m | 00:49AM0.81m | 1:02PM0.26m | 1:31AM0.73m | ||||||||
 |  | | |  |  | |  |  | | | | |  |  | | | | | | | |
 | — | — | 4:35 | — | — | 4:37 | — | — | 4:37 | — | — | 4:37 | — | — | 4:39 | — | — | 4:39 | — | — | 4:39 |
 | 6:58 | — | — | 6:58 | — | — | 6:58 | — | — | 6:57 | — | — | 6:57 | — | — | 6:55 | — | — | 6:55 | — | 6:54 |
mm | — | — | — | — | — | — | — | — | — | — | — | — | — | 1 | 1 | — | — | — | — | — | — |
Temp °C | 26 | 26 | 27 | 27 | 26 | 27 | 27 | 26 | 27 | 28 | 26 | 28 | 28 | 27 | 27 | 27 | 26 | 28 | 28 | 26 | 30 |
Feels °C | 28 | 30 | 31 | 30 | 28 | 29 | 28 | 27 | 30 | 29 | 27 | 29 | 28 | 29 | 29 | 28 | 28 | 31 | 30 | 30 | 31 |
Swell 1 Height (m) Direction Period (s) | SSW 16 | SSW 14 | SSW 13 | SSW 12 | SSW 11 | SSW 11 | SSW 10 | SSW 10 | SSW 9 | SE 9 | SE 9 | SSW 8 | SE 10 | SE 10 | SE 17 | SE 15 | SE 13 | SE 13 | SE 12 | SE 11 | SE 10 |
| kJ | 1107 | 569 | 302 | 206 | 109 | 66 | 59 | 38 | 34 | 3 | 3 | 7 | 4 | 4 | 142 | 444 | 290 | 242 | 210 | 174 | 153 |
Swell 2 Height (m) Direction Period (s) | SE 10 | SSE 10 | SE 10 | SE 10 | SE 9 | SE 9 | SE 12 | SE 10 | SE 10 | SE 11 | S 13 | SE 9 | SE 10 | SW 8 | SE 10 | ESE 9 | SW 8 | SW 8 | SW 8 | S 8 | S 7 |
| kJ | 32 | 9 | 4 | 4 | 3 | 3 | 6 | 4 | 4 | 5 | 3 | 3 | 16 | 3 | 4 | 15 | 2 | 2 | 2 | 1 | 1 |
Swell 3 Height (m) Direction Period (s) | SE 13 | SE 9 | SE 13 | ESE 12 | SE 12 | SE 12 | SE 9 | S 14 | S 14 | S 13 | E 11 | S 13 | SW 10 | SSE 9 | E 10 | — | SW 9 | S 8 | S 7 | S 7 | S 8 |
| kJ | 7 | 23 | 7 | 15 | 6 | 6 | 3 | 4 | 4 | 4 | 3 | 3 | 4 | 8 | 2 | — | 3 | 1 | 1 | 1 | 1 |
Wind waves Height (m) Direction Period (s) | — | — | — | — | — | — | S 2 | SSW 3 | SSW 3 | S 9 | SSW 4 | SSW 5 | S 5 | S 5 | S 5 | S 5 | S 4 | — | — | — | — |
| kJ | — | — | — | — | — | — | 1 | 1 | 1 | 81 | 25 | 24 | 64 | 31 | 28 | 53 | 9 | — | — | — | — |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 137 | 2 | 0 | 7 | 0 | 7 | 84 | 84 | 84 | 85 | 85 | 85 | 85 | 85 | 30 | 85 | 49 | 8 | 26 | 0 | 13 |
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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