The Knap surf break

The Knap surfForecast / Wales – South East / UK

information circle12 Day Weather and Surf, issued 6 am Tuesday 16 Sep 2025 BST
Forecast update in hr  min  s Forecast update imminent
Today's The Knap sea temperature is
17.5° C
(Which is 1.7°C warmer than normal for this time of year)


Best Forecast Surf Conditions for The Knap this week:

The most powerful waves expected at The Knap in the next 12 days are 0.7m 12s and forecast to arrive on Tuesday (Sep 16) at 1PM. Winds are predicted to be cross-shore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.4m 4s period and expected on Tuesday (Sep 23) at 10AM.

Wave TypeTime (BST) & Date Wave Height & Period
Next good surf (1 star+)--
Best Surf--
Most Powerful 1PM (Tue 16th Sep)2.5ft (0.7m) 12s

Table - best surf conditions forecast for The Knap over the next 12 days.

Updates in  hr  min  s Forecast update imminent

Short Range Forecast Light rain (total 9mm), mostly falling on Tue night. Warm (max 21°C on Thu morning, min 14°C on Tue night). Winds decreasing (fresh winds from the SW on Tue night, light winds from the S by Thu night).

Days 3-6 Weather Summary Heavy rain (total 34mm), heaviest during Sat morning. Warm (max 22°C on Fri afternoon, min 7°C on Sun morning). Winds increasing (calm on Fri night, near gales from the NNE by Sun morning).

Tuesday
16
Wednesday
17
Thursday
18
Friday
19
Saturday
20
Sunday
21
Monday
22
AMPMNightAMPMNightAMPMNightAMPMNightAMPMNightAMPMNightAMPMNight
Rating
(10 max)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Swell
Height Map
Wave Height (m) & direction (?)
0.8
W
0.7
W
0.4
W
0.6
WSW
0.7
WSW
0.6
W
0.5
WSW
0.5
WSW
0.5
W
0.4
WSW
0.4
WSW
0.3
WSW
0.2
W
0.3
WSW
0.2
W
0.3
WSW
0.3
WSW
0.2
W
0.1
W
0.1
W
0.2
NNE
Period(s) (?)1212118912121110101010998887763
Wave
Graph
(?)Metric surfscale
Energy (?)18113236548898817048313118615613134110
Wind
(km/h)
30
WNW
30
W
20
SSW
30
SW
25
SW
25
SW
25
SSW
20
WSW
10
S
10
S
10
WSW
10
WSW
5
ENE
15
ENE
20
NE
60
NNE
50
N
40
N
30
N
30
N
15
NNW
Wind State (?)
onshore
cross-onshore
cross-shore
cross-offshore
offshore
glassy
crosscrossoncross-
on
cross-
on
ononcross-
on
ononcross-
on
cross-
on
glasscross-
off
cross-
off
offoffcross-
off
cross-
off
cross-
off
cross-
off
High Tide
/ height (m)
2:39PM
8.42
3:33AM
8.15
4:16PM
8.59
4:59AM
8.61
5:28PM
9.28
5:59AM
9.36
6:20PM
10.06
6:44AM
10.10
7:01PM
10.75
7:22AM
10.71
7:37PM
11.27
7:56AM
11.15
8:11PM
11.56
Low Tide
/ height (m)
9:03PM
4.14
9:53AM
4.22
10:55PM
3.79
11:24AM
3.66
12:01AM
3.06
12:18PM
2.91
12:45AM
2.34
12:58PM
2.22
1:19AM
1.75
1:30PM
1.65
1:49AM
1.31
2:00PM
1.24
2:17AM
1.03
Tuesday
16
Wednesday
17
Thursday
18
Friday
19
Saturday
20
Sunday
21
Monday
22
Sunrise6:48--6:50--6:50--6:52--6:54--6:56--6:58--
Sunset-7:25--7:23--7:22--7:19--7:16--7:15--7:12-
part cloud
cloud
mod rain
light rain
light rain
cloud
part cloud
clear
clear
part cloud
clear
rain showers
mod rain
light rain
rain showers
mod rain
mod rain
rain showers
part cloud
part cloud
clear
Rain (mm)
--621------3944671---
Temp. °C15151517181821201720221715141410810121210
Feels °C (?)999131516181816192117161213-2-21555
  • Map Icons:
  • Break
  • Live Wave Height (m)
  • Live Wind Speed (km/h)
  • Surf Rating (10 Max)
  • Ocean Swells (m)
  • Wind Speed (km/h)
Map placeholder

Eyeball surf reportRecent Eyeball Surf Reports for Wales - South East

  1. weather stationWind Update Still cross-shore at The Knap (moderate winds from the WNW at Cardiff-Wales Airport 4 km from The Knap). A 1.2m windswell from the W

    The Knap
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1 h 47 min ago

28 km/h
WNW
Cross-Shore
Please reload the page to see if there are any updates.

FREE! Surf-Forecast.com widget for your website

The surf report / weather widget below is available to embed on third party websites free of charge and provides a summary of our The Knap surf forecast. Simply grab the html code snippet that we provide and paste it into your own site. You can choose your preferred language and metric/imperial units for the surf forecast feed to suit users of your site. Click here to get the code.


Information about the The Knap Surf forecast

The above surf forecast table for The Knap provides essential information for determining whether the surfing conditions will be good over the next 12 days. A general guide to surfing at The Knap can be found by selecting the local surf guide option on the grey menu. Our The Knap 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 (The Knap) 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 The Knap 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.

The Knap is 2 km (1 miles) from Barry. If you plan a holiday in Wales - South East, look for hotels and other accommodation in Barry. Barry has rooms for a wide range of budgets as well as car hire and transport links.

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