Kugenuma Rivermouth Surf Break

Lat Long: 35.31° N 139.47° E

Kugenuma Rivermouth Surf Forecast and Surf Report

Issued: 2 am 30 Jul 2026 (local time)

Forecast update in  hr  min

Today's Kugenuma Rivermouth sea temperature is
27.1° C
0.7° 

Kugenuma Rivermouth surf forecast is for near shore open water. Breaking waves will often be smaller at less exposed spots.


Kugenuma Rivermouth surf forecast from 29 Jul 2026:

  • Best quality surf: Wednesday 5 Aug, 9PM (local time) - 11ft (3.5m), 16s period, SSE swell with cross-offshore winds.
  • Most powerful swell: Thursday 6 Aug, 3AM (local time) - 11ft (3.5m), 17s period, SSE swell with 6,534 kJ wave energy.
  • Next surfable swell (1★+): Sunday 2 Aug, 6AM (local time) - 1.5ft (0.4m), 15s period with SE 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 Sunday (Aug 02) at 6AM. The primary swell is predicted to be 0.4m and 15s period with a secondary swell of 0.2m 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 3.5m 17s and forecast to arrive on Thursday (Aug 06) at 3AM. Winds are predicted to be offshore at the time the swell arrives.

Wave TypeTime (JST) & Date Wave Height & Period
Next good surf (1 star+) 6AM (Sun 2nd Aug)1.5ft (0.4m) 15s
Best Surf 9PM (Wed 5th Aug)11ft (3.5m) 16s
Most Powerful 3AM (Thu 6th Aug)11ft (3.5m) 17s

Table - best surf conditions forecast for Kugenuma Rivermouth over the next 16 days.


The Lowdown

G’day, Rusty here. Let’s be straight with you: the next few days at Kugenuma are a write-off. You’re looking at tiny, weak swell and poor surf conditions for the first week. The water’s sitting at a warm 81°, about normal for the time of year, so that’s not the problem—it’s just a total lack of energy.

Thursday the 30th and Friday the 31st are dead: ankle-biters under 2 ft with short period slop, and onshore winds making a mess of things. Saturday the 1st is glassy in the morning but still only 1.0 ft—barely a ripple. Sunday the 2nd morning shows a bit more life with a 1 ft SE swell and clean cross-off wind, but the combined energy is weak (69), and it’s still too ordinary to get excited about.

Monday the 3rd is where things start to shift. Offshores kick in from the NE at 15 mph, the swell jumps to 3 ft from the SE with a solid 16-second period, and combined energy climbs to moderate (438). It’s clean, but the swell’s still small. Tuesday the 4th builds further: 5 ft to 6 ft SE groundswell, period 16–17 seconds, offshore winds, and energy hitting 2126 (strong). This is where it gets interesting for intermediate and above—long-period SE swell will wrap in with shape, but at a beach/river setup like Kugenuma Rivermouth, that long period can make it break a bit straight. Still, clean and punchy.

Now, the standout window. Wednesday the 5th and Thursday the 6th are the real deal for experienced surfers. Wednesday morning hits 10 ft from the SSE with a 17-second period, strong offshore winds, and a combined energy of 4342—very strong. The swell direction (SSE) matches the optimum S direction closely, so it’s well-aligned. This is excellent, powerful surf, but at 10 ft, it’s for experts only. Thursday the 6th pushes even bigger at 12 ft from the S, energy at 5979, with NE cross-off winds keeping it clean in the morning. That’s a heavy, raw ocean—don’t even think about it unless you’ve got serious skills. For the average surfer, the best bet is Monday the 3rd through Tuesday the 4th, where the swell is manageable and the conditions are clean.

Friday the 7th still packs a punch at 8 ft from the S, but the onshore winds in the afternoon spoil it. Saturday the 8th drops back to a very clean 4 ft SW groundswell in the morning—great for a wider range of surfers, but the energy has faded to moderate (674). After that, it’s a slow slide into doldrums. From Sunday the 9th through Thursday the 14th, the swell peters out to under 3 ft, with weak combined energy and poor quality. By the 13th, you’ve got strong 18–28 mph offshores but only 2–2 ft of swell—a classic case of all wind, no wave. That’s more kite-surfing territory than paddle.

So, the standout: Wednesday the 5th through Thursday the 6th is the big swell window for experts only. For everyone else, aim for Monday the 3rd or Tuesday the 4th. The crowd factor at Kugenuma is “often,” so expect company on those better days.

Rusty.

Short Range Forecast

Light rain (total 2mm), mostly falling on Thu afternoon. Warm (max 30°C on Thu morning, min 28°C on Thu morning). Wind will be generally light.

Days 4-6 Weather Summary

Mostly dry. Warm (max 31°C on Sun morning, min 24°C on Sun night). Wind will be generally light.

Thursday
30
Friday
31
Saturday
1
Sunday
2
Monday
3
Tuesday
4
Wednesday
5
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
Rating
(10 max)
0
0
0
0
0
0
0
0
0
1
0
2
2
1
3
3
3
3
5
5
!
Swell
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Wave
Height (m)
Direction
Period (s)
0.4
SSW
7
0.3
SSW
7
0.5
S
7
0.5
S
6
0.4
SSW
6
0.4
SSW
6
0.3
SSW
7
0.4
SSW
6
0.3
SE
17
0.4
SE
16
0.5
SE
15
0.7
SE
17
0.9
SE
16
1
SE
17
1.2
SE
17
1.6
SE
16
1.8
SE
17
2.3
SE
17
3
SSE
17
3
SSE
17
3.5
SSE
17
Wave Graph
Metric surfscale
Energy kJ
18
10
23
22
14
13
9
12
46
64
109
281
386
573
802
1261
1972
2864
4342
5259
6043
Wind (km/h)
5
ENE
10
SSW
5
NNE
10
NE
15
S
5
ESE
5
E
15
S
5
SE
5
E
15
S
25
NE
25
NE
25
NE
25
NNE
25
NE
25
NE
25
NE
20
NNE
20
NE
15
NE
Wind State
cross-off
on
glassy
off
cross-on
cross
glassy
on
glassy
cross-off
cross-on
off
off
cross-off
off
off
cross-off
off
off
cross-off
cross-off
High Tide
6:27PM1.45m
5:20AM1.52m
6:46PM1.47m
6:02AM1.50m
7:08PM1.49m
6:46AM1.45m
7:32PM1.50m
7:33AM1.36m
8:00PM1.50m
8:27AM1.25m
8:29PM1.48m
9:35AM1.12m
9:01PM1.45m
Low Tide
11:38AM0.13m
11:49PM0.86m
12:07PM0.19m
00:21AM0.76m
12:35PM0.28m
00:57AM0.67m
1:03PM0.40m
1:38AM0.60m
1:31PM0.54m
2:25AM0.56m
1:56PM0.69m
3:24AM0.54m
2:16PM0.86m
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thunderstorm
thunderstorm
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clear
clear
part cloud
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part cloud
clear
part cloud
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thunderstorm
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
4:48
4:48
4:50
4:50
4:50
4:52
4:52
<span class="translation_missing" title="translation missing: en.weather_tables.sunset">Sunset</span>
6:47
6:46
6:45
6:45
6:44
6:43
6:42
 mm
1
1
2
Temp °C
30
29
28
30
30
28
30
30
29
31
30
26
27
28
25
29
30
26
29
31
27
Feels °C
32
31
32
32
32
31
33
32
33
34
32
25
26
27
23
28
30
26
30
32
29
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  • Live Wave Height (m)
  • Live Wind Speed (km/h)
  • Surf Rating (10 Max)
  • Ocean Swells (m)
  • Wind Speed (km/h)
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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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