Backdoor Surf Break

Lat Long: 38.92° N 9.43° W

Backdoor Surf Forecast and Surf Report

Issued: 12 am 18 Aug 2026 (local time)

Forecast update in  hr  min

Today's Backdoor sea temperature is
19.6° C
1.0° 

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


Backdoor surf forecast from 18 Aug 2026:

  • Best quality surf: Tuesday 18 Aug, 10PM (local time) - 4ft (1.2m), 8s period, NNW swell with glassy winds.
  • Most powerful swell: Sunday 23 Aug, 10AM (local time) - 8ft (2.5m), 8s period, NNW swell with 954 kJ wave energy.
  • Next surfable swell (1★+): Tuesday 18 Aug, 10PM (local time) - 4ft (1.2m), 8s period with NNW swell.

Best Forecast Surf Conditions for Backdoor this week:

The surf forecast for Backdoor over the next 16 days: The first swell (rated 1 star or higher) is forecast to arrive on Tuesday (Aug 18) at 10PM. The primary swell is predicted to be 1.2m and 8s period with a secondary swell of 0.3m and 8s. The wind is predicted to be glassy as the swell arrives.

The most powerful waves expected at Backdoor in the next 16 days are 2.5m 8s and forecast to arrive on Sunday (Aug 23) at 10AM. Winds are predicted to be cross-shore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.2m 16s period and expected on Tuesday (Aug 18) at 4PM.

Wave TypeTime (WEST) & Date Wave Height & Period
Next good surf (1 star+)10PM (Tue 18th Aug)4ft (1.2m) 8s
Best Surf10PM (Tue 18th Aug)4ft (1.2m) 8s
Most Powerful10AM (Sun 23rd Aug)8ft (2.5m) 8s

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


The Lowdown

Alright, let's get real about the next couple weeks. We got a window, but it's not going to be a classic. The ocean is going to be doing its own thing for most of the period, so you gotta be picky.

The outlook starts off rough. Tuesday the 18th, there's some swell, around 5ft from the NNW with a short, weak 8-second period. The energy is weak to moderate at 285. But the wind is cross and cross-on, so it’s gonna be a choppy mess. Not worth paddling out. Wednesday is smaller and weaker, still a messy cross-shore. Thursday morning, we finally get a bit of glass. The swell drops to 2ft from the WNW, period 9 seconds, and the energy is down to 73. It’s tiny, but it’s clean. That's your only real chance in this first stretch, even if it’s just a grovel session.

Then the wind turns on from the NNW and it just ruins everything. Friday the 21st through the 24th, we’ve got a solid pulse of swell – building from 6ft to 8ft – and the energy jumps into the strong zone (495, 753, 811, up to 961). But it's all for nothing. The NNW wind is howling at 20-25 mph, creating a lumpy, cross-chop mess. The period is short, around 8 to 10 seconds, so it's not going to be organized anyway. It's just a mess. All that size and nowhere to go.

We then get a bit of a lull, but the wind stays cross-shore, so nothing cleans up for more than a morning. The next week is the same story. A couple of small pulses, but the cross-winds and cross-on winds never let up. There’s a moment on the 29th of August, a Saturday morning, where the wind goes light and onshore, with 5ft of NNW swell, but the comment says it's marginal and the tide might mess it up. It's a gamble, not a recommendation.

Honestly, if you look at the whole 16 days, the only standout is that tiny, clean window on Thursday morning, the 20th of August. 2ft is nothing to write home about, but with the glassy conditions, it will be the only time you get a truly clean wave. After that, it’s a long stretch of poor conditions until the very end of the period. On the 2nd of September, there's a pulse of 5ft from the NW with a 10-second period and moderate energy at 498, but the wind is onshore. It’s just another tease.

So, my call is this: if you can, paddle out Thursday morning for some clean, tiny waves. It will be all about finesse, not power. For the rest, you might as well leave the board in the car. This is a stretch where the ocean just doesn’t have its act together.

Rusty.

Short Range Forecast

Mostly dry. Warm (max 23°C on Tue morning, min 20°C on Mon night). Wind will be generally light.

Days 4-6 Weather Summary

Mostly dry. Warm (max 20°C on Fri morning, min 18°C on Sat night). Mainly strong winds.

Tuesday
18
Wednesday
19
Thursday
20
Friday
21
Saturday
22
Sunday
23
Monday
24
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
Rating
(10 max)
1
0
1
0
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Swell
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Wave
Height (m)
Direction
Period (s)
1.5
NNW
8
1.4
NNW
8
1.1
NNW
8
0.9
NNW
7
0.9
NNW
7
0.5
WNW
9
0.6
WNW
9
0.6
WNW
9
1.9
NW
8
1.7
NNW
7
1.9
NNW
10
1.9
NNW
10
2
NNW
10
1.8
NNW
9
2.4
NNW
8
2.5
NNW
8
2.2
NNW
8
2.1
NNW
8
2
NNW
8
1.7
NNW
8
1.5
NNW
7
Wave Graph
Metric surfscale
Energy kJ
270
231
138
94
70
50
62
61
392
263
706
692
772
539
744
954
634
481
463
302
229
Wind (km/h)
15
SSW
20
SW
5
SSW
5
SSW
15
SW
5
NE
5
SW
15
W
30
N
30
NNW
35
NNW
30
NNW
30
NNW
35
NNW
40
NNW
40
NNW
35
NNW
35
NNW
30
N
25
NNW
30
N
Wind State
cross
cross-on
glassy
cross
cross-on
glassy
glassy
on
cross
cross
cross
cross
cross
cross
cross
cross
cross
cross
cross
cross-on
cross
High Tide
7:02AM2.50m
7:21PM2.44m
7:44AM2.32m
8:08PM2.18m
8:37AM2.15m
9:12PM1.98m
9:50AM2.03m
10:42PM1.88m
11:22AM2.03m
00:11AM1.94m
12:36PM2.16m
1:11AM2.08m
1:28PM2.34m
1:54AM2.25m
Low Tide
1:04PM0.59m
1:27AM0.69m
1:50PM0.80m
2:12AM0.91m
2:50PM1.00m
3:15AM1.09m
4:18PM1.11m
4:48AM1.16m
5:56PM1.07m
6:14AM1.07m
7:03PM0.92m
7:12AM0.91m
7:48PM0.74m
clear
clear
clear
clear
clear
clear
clear
clear
part cloud
clear
clear
clear
clear
clear
clear
clear
clear
clear
clear
clear
clear
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
6:52
6:54
6:54
6:56
6:56
6:56
6:58
<span class="translation_missing" title="translation missing: en.weather_tables.sunset">Sunset</span>
8:29
8:27
8:25
8:24
8:22
8:22
8:20
 mm
Temp °C
23
23
21
23
23
21
22
22
19
20
20
19
20
20
19
20
20
19
21
21
18
Feels °C
23
22
23
23
23
24
22
22
15
16
15
15
16
14
13
15
14
14
18
18
15
  • Map Icons:
  • Break
  • 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 Backdoor Surf forecast

The above surf forecast table for Backdoor provides essential information for determining whether the surfing conditions will be good over the next 16 days. A general guide to surfing at Backdoor can be found by selecting the local surf guide option on the grey menu. Our Backdoor 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 (Backdoor) 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 Backdoor 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.

Backdoor is 14 km (9 miles) from the city of Sintra. If you plan a holiday in Ericeira, look for hotels and other accommodation in Sintra. Sintra has rooms for a wide range of budgets as well as car hire and transport links.

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