Surf Forecasts:
Kugenuma Rivermouth surf forecast from 13 Aug 2026:
- Best quality surf: Friday 14 Aug, 3PM (local time) - 1.5ft (0.4m), 9s period, SSW swell with cross-offshore winds.
- Most powerful swell: Saturday 15 Aug, 6PM (local time) - 3ft (0.9m), 9s period, ESE swell with 151 kJ wave energy.
- Next surfable swell (1★+): Friday 14 Aug, 3PM (local time) - 1.5ft (0.4m), 9s 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 Friday (Aug 14) at 3PM. The primary swell is predicted to be 0.4m and 9s period with a secondary swell of 0.3m and 6s. Another secondary swell of 0.6m and 6s 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 0.9m 9s and forecast to arrive on Saturday (Aug 15) at 6PM. Winds are predicted to be cross-shore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.3m 2s period and expected on Sunday (Aug 16) at 6AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 3PM (Fri 14th Aug) | 1.5ft (0.4m) 9s |
| Best Surf | 3PM (Fri 14th Aug) | 1.5ft (0.4m) 9s |
| Most Powerful | 6PM (Sat 15th Aug) | 3ft (0.9m) 9s |
Table - best surf conditions forecast for Kugenuma Rivermouth over the next 16 days.
The Lowdown
Alright, let's talk about Kugenuma Rivermouth over the next couple of weeks. Honestly, the first part of this outlook is a bit of a bummer. From Thursday the 13th all the way through to Saturday the 22nd, we’re in a real flat spell. You'll see some clean, glassy mornings, but the swell is just pathetic—0.3 to 0.5 feet. It's nearly ten days where you’re not gonna find anything worth paddling out for.
The water temp is about 81°, which is pretty normal for this time of year. Nothing special.
Then, things wake up. Sunday the 23rd, we get a nice little pulse: a 4 foot swell from the SSE with a long 15-second period. The combined energy is 865, which is a decent moderate level, and with a light offshore breeze, it’s gonna be clean. That long period will work well at the river mouth.
The real standout, though, is Monday the 24th. We're looking at a 5 foot swell from the SSE, a 14-second period, and a light cross-offshore wind. The energy reading is a strong 1805. This is gonna produce excellent, clean waves for experienced surfers. This is the day to circle on your calendar. It's too big for the groms, but if you know what you're doing, you're in for a treat.
Heading into the end of the month, it gets serious. Wednesday the 26th morning has an 8 foot SSW groundswell with a clean offshore wind, and the energy is a whopping 3202. That's expert-level stuff. And Thursday the 27th is just massive: a 21 foot SSE groundswell, glassy, but the energy is a staggering 17295. That is way too big for this spot—strictly a spectator event. It drops back to about 4 feet on Friday the 28th, but the onshore wind chops it up.
So, there's a long wait until the 23rd, but trust me, Monday the 24th is the session you want to be on. Don't miss it.
Rusty.
Short Range ForecastHeavy rain (total 33mm), heaviest during Thu afternoon. Warm (max 29°C on Thu afternoon, min 24°C on Sat night). Wind will be generally light. | Days 5-7 Weather SummaryMostly dry. Warm (max 29°C on Sun afternoon, min 23°C on Sun night). Wind will be generally light. | |||||||||||||||||||
Thu 13 | Friday 14 | Saturday 15 | Sunday 16 | Monday 17 | Tuesday 18 | Wednesday 19 | ||||||||||||||
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 9 | SSW 9 | SSW 9 | ESE 6 | SSW 11 | ESE 9 | SSW 9 | SSW 9 | SSW 9 | SSW 10 | ESE 10 | SSW 8 | SSW 8 | S 9 | S 3 | SSW 8 | SSW 8 | SSW 8 | S 10 |
Wave Graph  | ||||||||||||||||||||
 kJ | 31 | 28 | 16 | 29 | 22 | 40 | 101 | 28 | 29 | 28 | 31 | 21 | 14 | 14 | 7 | 7 | 6 | 6 | 6 | 7 |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-off | off | off | cross-off | cross-off | cross-off | cross-off | off | off | cross-off | cross-off | off | cross-on | cross-on | on | on | on | glassy | on | cross-on |
High Tide | 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 | 8:48AM1.21m | 8:14PM1.50m | |||||||
Low Tide | 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 | 1:44PM0.84m | ||||||||
 |  | | | |  | |  |  | |  | | | | | |  | | | | |
 | — | — | 5:00 | — | — | 5:00 | — | — | 5:01 | — | — | 5:01 | — | — | 5:03 | — | — | 5:03 | — | — |
 | 6:34 | — | — | 6:32 | — | — | 6:31 | — | — | 6:30 | — | — | 6:29 | — | — | 6:28 | — | — | 6:27 | — |
mm | 8 | 9 | 1 | 2 | 9 | — | 3 | 1 | — | — | — | — | — | — | — | — | — | — | — | — |
Temp °C | 29 | 27 | 28 | 28 | 27 | 28 | 27 | 25 | 27 | 29 | 25 | 26 | 26 | 26 | 27 | 27 | 27 | 28 | 28 | 28 |
Feels °C | 32 | 30 | 29 | 30 | 30 | 29 | 27 | 25 | 26 | 28 | 25 | 27 | 27 | 28 | 27 | 27 | 28 | 32 | 29 | 30 |
Swell 1 Height (m) Direction Period (s) | SSW 10 | SSW 9 | SSW 9 | SSW 9 | SSW 9 | SSW 11 | SSW 10 | SE 8 | SSW 9 | SSW 9 | SSW 10 | SSW 9 | SSW 8 | SSW 8 | SSW 8 | SE 10 | SSW 8 | SSW 8 | SE 10 | SSE 7 |
| kJ | 31 | 28 | 16 | 29 | 16 | 40 | 34 | 20 | 29 | 28 | 31 | 16 | 14 | 14 | 7 | 4 | 6 | 6 | 4 | 5 |
Swell 2 Height (m) Direction Period (s) | E 10 | ESE 9 | SE 6 | SE 6 | SSE 10 | SE 6 | SSE 8 | SSW 9 | SE 9 | ESE 9 | SE 10 | ESE 10 | ESE 10 | SSE 3 | SE 10 | — | SE 10 | SE 10 | SSW 8 | SE 10 |
| kJ | 2 | 8 | 5 | 5 | 20 | 11 | 26 | 28 | 13 | 16 | 28 | 21 | 10 | 1 | 4 | — | 4 | 4 | 6 | 4 |
Swell 3 Height (m) Direction Period (s) | SE 12 | S 12 | S 12 | SE 11 | SE 5 | SSE 9 | SE 10 | ESE 9 | SE 12 | SSE 11 | SSE 11 | SSE 11 | SE 11 | SE 11 | S 7 | — | S 7 | SE 6 | — | S 10 |
| kJ | 5 | 11 | 11 | 5 | 4 | 16 | 4 | 9 | 5 | 12 | 12 | 12 | 5 | 4 | 1 | — | 1 | 2 | — | 7 |
Wind waves Height (m) Direction Period (s) | ENE 3 | — | — | ESE 6 | ESE 6 | — | ESE 9 | — | NE 2 | — | — | — | SSE 2 | — | S 9 | S 3 | SSW 3 | SSW 3 | S 3 | SSW 3 |
| kJ | 1 | — | — | 28 | 22 | — | 101 | — | 1 | — | — | — | 1 | — | 7 | 7 | 3 | 1 | 4 | 3 |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 45 | 30 | 45 | 0 | 0 | 18 | 64 | 8 | 45 | 45 | 0 | 45 | 26 | 30 | 26 | 85 | 84 | 84 | 85 | 26 |
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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