Surf Forecasts:
Backdoor surf forecast from 18 Aug 2026:
- Best quality surf: Wednesday 19 Aug, 1AM (local time) - 4ft (1.2m), 8s period, NNW swell with glassy winds.
- Most powerful swell: Sunday 23 Aug, 7AM (local time) - 10ft (3.0m), 9s period, NNW swell with 1,176 kJ wave energy.
- Next surfable swell (1★+): Wednesday 19 Aug, 1AM (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 Wednesday (Aug 19) at 1AM. 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 3.0m 9s and forecast to arrive on Sunday (Aug 23) at 7AM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.2m 15s period and expected on Thursday (Aug 20) at 10PM.
| Wave Type | Time (WEST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 1AM (Wed 19th Aug) | 4ft (1.2m) 8s |
| Best Surf | 1AM (Wed 19th Aug) | 4ft (1.2m) 8s |
| Most Powerful | 7AM (Sun 23rd Aug) | 10ft (3.0m) 9s |
Table - best surf conditions forecast for Backdoor over the next 16 days.
The Lowdown
Alright folks, let’s have a look at what’s coming down the pipe at Backdoor. I’ll be honest with you, this isn’t a classic run of form. The whole sixteen days is pretty much a write-off for anything decent. The first real suggestion of surf that's even worth paddling out for doesn’t show up until Wednesday the 2nd of September, and even then it's a marginal call. That’s a long dry spell of over a week with nothing on offer.
The water temp is about normal for this time of year, sitting at 68°F.
So, for most of this outlook, the winds are a real problem. We've got a persistent run of cross and cross-onshore breezes, often fresh and strong, turning the surface into lumpy chop. There's some size at times, especially around the 21st to the 24th of August, with swell heights getting up over 7ft and combined energy hitting some decent numbers (like 961 on the 21st afternoon), but the wind just ruins it. That kind of size with those winds? It’s not going to be clean.
You see a peak of 8ft on the morning of the 23rd, but again, it’s crossed up and choppy. For a reef break like this, that’s not a good look. It's a high-performance wave and these conditions are not for it.
The only glimmer, and I mean only, is Wednesday the 2nd of September. The morning shows a 4ft swell from the NW with a 9-second period. The energy is still moderate (393), but the wind finally drops to a gentle breeze. It’s still a cross-shore wind, so it’s not perfect, but it’s the only period in the whole outlook where the winds are light enough for the surface to be anything other than messy. The rating is a 1/10, so don’t expect anything epic. It’s that spot where you might just get a few.
Backdoor is a very consistent spot, which is why the blank run here is so painful. The swell just won’t line up with the wind. For the first week and a half, I’d look elsewhere. This is one of those stretches where the forecast is telling you to leave the board in the car.
Rusty
Short Range ForecastMostly dry. Warm (max 23°C on Tue afternoon, min 18°C on Thu night). Winds increasing (calm on Tue night, fresh winds from the NNW by Thu night). | Days 5-7 Weather SummaryMostly dry. Warm (max 21°C on Mon morning, min 18°C on Fri night). Mainly fresh winds. | |||||||||||||||||||
Tue 18 | Wednesday 19 | Thursday 20 | Friday 21 | Saturday 22 | Sunday 23 | Monday 24 | ||||||||||||||
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) | NNW 8 | NNW 8 | NNW 7 | NNW 7 | NNW 6 | WNW 9 | NNW 5 | NNW 7 | NNW 8 | NNW 10 | NNW 8 | NNW 8 | NNW 8 | NNW 8 | NNW 9 | NNW 8 | NNW 9 | NNW 9 | NNW 8 | NNW 7 |
Wave Graph  | ||||||||||||||||||||
 kJ | 237 | 159 | 94 | 68 | 50 | 62 | 61 | 344 | 447 | 961 | 644 | 763 | 707 | 820 | 975 | 597 | 815 | 785 | 476 | 327 |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | glassy | cross-on | on | glassy | cross-on | cross | cross | cross | cross | cross | cross | cross | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on | cross |
High Tide | 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 | 1:27AM0.69m | 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 | ||||||||
 |  | | |  |  | | | | | | | | | | | | | | | |
 | — | — | 6:54 | — | — | 6:54 | — | — | 6:56 | — | — | 6:56 | — | — | 6:56 | — | — | 6:58 | — | — |
 | 8:29 | — | — | 8:27 | — | — | 8:25 | — | — | 8:24 | — | — | 8:22 | — | — | 8:22 | — | — | 8:20 | — |
mm | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
Temp °C | 23 | 21 | 22 | 22 | 20 | 22 | 21 | 19 | 20 | 20 | 18 | 20 | 20 | 19 | 20 | 20 | 19 | 21 | 21 | 19 |
Feels °C | 23 | 23 | 22 | 22 | 21 | 21 | 19 | 14 | 15 | 15 | 13 | 16 | 16 | 14 | 17 | 17 | 15 | 17 | 17 | 16 |
Swell 1 Height (m) Direction Period (s) | NNW 8 | NNW 8 | NNW 7 | NNW 7 | NNW 6 | NNW 5 | WNW 9 | W 9 | NNW 11 | SSW 15 | SSW 14 | WNW 9 | WNW 9 | WNW 9 | SW 13 | SW 13 | SW 13 | SW 13 | SW 13 | SW 12 |
| kJ | 237 | 159 | 94 | 68 | 41 | 24 | 61 | 39 | 242 | 21 | 18 | 25 | 26 | 16 | 7 | 7 | 7 | 7 | 7 | 6 |
Swell 2 Height (m) Direction Period (s) | SSW 16 | WNW 8 | WNW 8 | NW 10 | WNW 9 | WNW 9 | NW 11 | NW 12 | SSW 15 | — | — | SSW 14 | SSW 14 | SSW 14 | SSW 13 | — | — | — | — | — |
| kJ | 24 | 13 | 12 | 27 | 50 | 62 | 30 | 37 | 21 | — | — | 20 | 20 | 20 | 18 | — | — | — | — | — |
Swell 3 Height (m) Direction Period (s) | WNW 8 | SSW 15 | SW 14 | WNW 8 | SSW 13 | NNW 12 | SW 13 | NNW 10 | — | — | — | — | — | — | — | — | — | — | — | — |
| kJ | 6 | 21 | 33 | 6 | 17 | 14 | 7 | 10 | — | — | — | — | — | — | — | — | — | — | — | — |
Wind waves Height (m) Direction Period (s) | SW 3 | — | — | — | — | — | NNW 5 | NNW 7 | NNW 8 | NNW 10 | NNW 8 | NNW 8 | NNW 8 | NNW 8 | NNW 9 | NNW 8 | NNW 9 | NNW 9 | NNW 8 | NNW 7 |
| kJ | 2 | — | — | — | — | — | 59 | 344 | 447 | 961 | 644 | 763 | 707 | 820 | 975 | 597 | 815 | 785 | 476 | 327 |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 22 | 0 | 1 | 407 | 0 | 1 | 407 | 407 | 240 | 426 | 240 | 230 | 377 | 230 | 128 | 218 | 198 | 200 | 455 | 28 |
Best forecast wave conditions in Ericeira | ||||||||||||||||||||
Best forecast wave conditions in Portugal | ||||||||||||||||||||
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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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