Surf Forecasts:
Kugenuma Rivermouth surf forecast from 22 Aug 2026:
- Best quality surf: Monday 24 Aug, 6AM (local time) - 1.5ft (0.5m), 16s period, SSE swell with glassy winds.
- Most powerful swell: Tuesday 25 Aug, 12AM (local time) - 5.5ft (1.7m), 15s period, SSE swell with 1,275 kJ wave energy.
- Next surfable swell (1★+): Monday 24 Aug, 6AM (local time) - 1.5ft (0.5m), 16s 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 6AM. The primary swell is predicted to be 0.5m and 16s period with a secondary swell of 0.5m and 12s. 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 15s and forecast to arrive on Tuesday (Aug 25) 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 0.3m 2s period and expected on Saturday (Aug 29) at 6AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 6AM (Mon 24th Aug) | 1.5ft (0.5m) 16s |
| Best Surf | 6AM (Mon 24th Aug) | 1.5ft (0.5m) 16s |
| Most Powerful | 12AM (Tue 25th Aug) | 5.5ft (1.7m) 15s |
Table - best surf conditions forecast for Kugenuma Rivermouth over the next 16 days.
The Lowdown
Alright, Rusty here. Let's have a look at what's on the cards for the Kugenuma Rivermouth (Japan).
Right now, it’s a bit of a flat spell, to be honest. We’re looking at a few days of nothing really worth paddling out for. Sunday and Monday are both a write-off with tiny, weak waves and poor conditions. Tuesday picks up a little in size, but the wind is straight onshore and messy, so it’s not going to be any good. The wait will be a long one – we're talking nearly a week of pretty ordinary stuff.
The first real glimmer of hope comes around Friday, August 28th. The swell is still small, around 2ft to 3ft from the S, but we finally get some clean conditions. The morning has a gentle offshore breeze from the NNE, and by the afternoon, it goes glassy. It's not going to be big, but for a beginner-friendly spot like this, those are your windows. The wave energy is still weak though, only about 105 to 122.
Saturday the 29th keeps the trend going with clean surf in the morning thanks to a light cross-offshore wind, and a moderate offshore in the afternoon. Still small, still weak energy, but it's surfable and clean.
The next real standout doesn't show up until Friday, September 4th. The swell builds to about 4ft from the S, and we've got a solid, consistent moderate offshore wind from the NNE all day. The wave energy is moderate (540 to 549), and the conditions are looking very good. That Friday afternoon session is the pick of the forecast, with clean, offshore lines. It’s not huge, so it’s still fine for all abilities, but for this stretch of coast, it's about as good as it gets in this outlook.
The weekend after that, September 5th and 6th, stays clean with offshore winds, but the swell drops back down. It’ll be fun enough for a longboard or a summer grovel board, but nothing to get overly excited about.
So to sum it up: the first week is mostly a dud. Hang tight. Your best bet is that Friday afternoon, September 4th, at the rivermouth. Clean, offshore, and a bit of push.
Rusty.
Short Range ForecastMostly dry. Warm (max 29°C on Tue morning, min 26°C on Sun morning). Wind will be generally light. | Days 4-6 Weather SummaryLight rain (total 2mm), mostly falling on Thu night. Warm (max 30°C on Wed afternoon, min 24°C on Fri afternoon). Winds decreasing (fresh winds from the SSW on Wed afternoon, light winds from the WSW by Thu night). | ||||||||||||||||||||
Sunday 23 | Monday 24 | Tuesday 25 | Wednesday 26 | Thursday 27 | Friday 28 | Saturday 29 | |||||||||||||||
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 9 | SE 13 | SE 13 | SSE 18 | SSE 17 | SSE 15 | S 14 | SSE 13 | S 13 | S 12 | SSW 13 | SSW 12 | SSW 11 | SW 11 | S 8 | S 8 | S 8 | S 8 | S 9 | S 9 | S 9 |
Wave Graph  | |||||||||||||||||||||
 kJ | 25 | 27 | 82 | 254 | 486 | 1275 | 899 | 590 | 670 | 416 | 762 | 250 | 113 | 58 | 66 | 50 | 47 | 51 | 59 | 57 | 38 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-off | cross-on | cross-on | cross-on | on | on | on | on | on | on | on | on | on | on | on | off | cross-off | cross-off | cross-off | cross-on | cross |
High Tide | 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 | 4:44AM1.53m | 5:42PM1.49m | 5:22AM1.55m | 5:58PM1.52m | ||||||||
Low Tide | 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 | 11:19AM0.31m | 11:29PM0.65m | 11:43AM0.38m | 11:57PM0.54m | ||||||||
 | |  |  | |  | | | | | | | | |  |  |  | | | | | |
 | 5:05 | — | — | 5:07 | — | — | 5:07 | — | — | 5:09 | — | — | 5:09 | — | — | 5:09 | — | — | 5:11 | — | — |
 | — | 6:22 | — | — | 6:21 | — | — | 6:19 | — | — | 6:17 | — | — | 6:16 | — | — | 6:15 | — | — | 6:14 | — |
mm | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 1 | 1 | — | — | — | — | — |
Temp °C | 28 | 28 | 26 | 27 | 28 | 27 | 29 | 29 | 28 | 28 | 30 | 28 | 29 | 30 | 27 | 27 | 25 | 24 | 25 | 26 | 25 |
Feels °C | 31 | 30 | 29 | 31 | 29 | 28 | 30 | 30 | 28 | 28 | 30 | 29 | 29 | 31 | 31 | 28 | 26 | 25 | 26 | 28 | 27 |
Swell 1 Height (m) Direction Period (s) | SSW 9 | SSW 8 | SE 13 | SSE 12 | SSE 13 | SSE 15 | S 14 | SSE 13 | S 13 | S 12 | SSE 9 | SSW 12 | S 8 | S 8 | S 8 | S 8 | S 8 | S 8 | S 9 | S 9 | S 9 |
| kJ | 25 | 14 | 82 | 133 | 282 | 1275 | 899 | 590 | 670 | 416 | 34 | 250 | 61 | 33 | 66 | 50 | 47 | 51 | 59 | 57 | 38 |
Swell 2 Height (m) Direction Period (s) | SE 10 | SE 13 | SSW 8 | SSE 18 | SSE 17 | ESE 11 | S 17 | S 16 | ESE 13 | E 12 | SSE 9 | SSE 9 | SSW 11 | SW 11 | SW 10 | SSE 10 | SSE 10 | SSE 10 | SSE 11 | SSE 11 | SSE 10 |
| kJ | 4 | 27 | 14 | 254 | 486 | 25 | 351 | 401 | 33 | 3 | 94 | 31 | 113 | 58 | 16 | 9 | 9 | 9 | 11 | 12 | 11 |
Swell 3 Height (m) Direction Period (s) | SE 13 | SE 10 | SSE 18 | SSE 15 | SW 9 | E 15 | ESE 14 | SW 10 | SW 9 | SSE 10 | ESE 12 | E 16 | SSE 10 | SSE 10 | SSE 10 | SW 10 | S 11 | SE 13 | S 13 | E 6 | E 7 |
| kJ | 7 | 4 | 31 | 84 | 3 | 17 | 66 | 14 | 3 | 137 | 27 | 5 | 18 | 10 | 9 | 4 | 3 | 7 | 3 | 7 | 1 |
Wind waves Height (m) Direction Period (s) | — | SSE 4 | — | — | SSW 8 | SW 4 | SW 4 | SSW 4 | SSW 4 | SSW 4 | SSW 13 | SSW 5 | — | S 4 | — | — | — | NNE 2 | NE 2 | — | — |
| kJ | — | 2 | — | — | 21 | 15 | 10 | 29 | 15 | 6 | 762 | 29 | — | 22 | — | — | — | 1 | 1 | — | — |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 63 | 57 | 57 | 13 | 24 | 85 | 7 | 88 | 484 | 7 | 7 | 85 | 19 | 7 | 85 | 0 | 0 | 0 | 45 | 0 | 0 |
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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