Surf Forecasts:
Cape Northumberland surf forecast from 15 Aug 2026:
- Best quality surf: Friday 21 Aug, 3PM (local time) - 13ft (4.0m), 17s period, WSW swell with onshore winds.
- Most powerful swell: Saturday 22 Aug, 6PM (local time) - 15ft (4.5m), 17s period, SW swell with 12,781 kJ wave energy.
- Next surfable swell (1★+): Sunday 16 Aug, 3AM (local time) - 10ft (3.0m), 14s period with SW swell.
Best Forecast Surf Conditions for Cape Northumberland this week:
The surf forecast for Cape Northumberland over the next 16 days: The first swell (rated 1 star or higher) is forecast to arrive on Sunday (Aug 16) at 3AM. The primary swell is predicted to be 3.0m and 14s period with a secondary swell of 0.6m and 15s. The wind is predicted to be glassy as the swell arrives.
The most powerful waves expected at Cape Northumberland in the next 16 days are 4.5m 17s and forecast to arrive on Saturday (Aug 22) at 6PM. Winds are predicted to be onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.2m 5s period and expected on Wednesday (Aug 19) at 3AM.
| Wave Type | Time (ACST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 3AM (Sun 16th Aug) | 10ft (3.0m) 14s |
| Best Surf | 3PM (Fri 21st Aug) | 13ft (4.0m) 17s |
| Most Powerful | 6PM (Sat 22nd Aug) | 15ft (4.5m) 17s |
Table - best surf conditions forecast for Cape Northumberland over the next 16 days.
The Lowdown
G’day, I’m Rusty. Let’s get into what’s coming up for Cape Northumberland.
Look, we’ve got a solid run of swell on the way, but the wind is going to be the story for a lot of it. The first week is a bit of a mixed bag, with some real quality windows for the experienced crew, then a few days where it gets messy, before a couple of standout sessions in the second week that are worth circling on the calendar. The water temp is sitting about average for this time of year, so nothing unusual there.
The best bet for the first few days is Sunday the 16th. Sunday morning is looking clean with a light offshore breeze from the ENE at 6 mph, and a solid 8 ft SW groundswell rolling in at 14 seconds. The combined energy is strong at 2927, so there’s plenty of push. It’s a powerful reef wave here, so this is one for the advanced crew only. Crowds are possible, but with that size and the reef, it’ll thin out. Sunday afternoon sees the wind swing SE and pick up to 19 mph, turning it cross-offshore, but it stays clean. Still good, but the morning is the pick.
Monday the 17th is another cracker for the experienced. The morning session has a light offshore breeze again, 9 mph from the ENE, with a 8 ft SW groundswell that has stretched out to a very long 16-second period. The energy is up to 3243. That long period means the waves will have real shape and power, but it can also close out a bit if you’re not on the right part of the reef. Still, for the guys who know the line-up, it’s going to be pumping. The afternoon is a step down with a cross-offshore breeze, but still clean and rideable.
Tuesday the 18th sees the wind get stronger from the NE at 19 mph, making it cross-offshore, but the swell is dropping to 7 ft. It’s still got a long period of 17 seconds, but the energy is down to 2426. The quality is only marginal. By Wednesday the 19th, the wind is howling from the NNE at 25 mph, with a messy cross-offshore breeze and the swell dropping to 4 ft. The energy is weak at 674. It’s a write-off. Thursday the 20th and Friday the 21st are no better – the wind is onshore or cross-onshore, and the swell is either small or way too big. Friday afternoon actually has a massive 13 ft SW swell with a 17-second period and energy hitting 18007, but it’s blowing onshore at 25 mph from the WSW. That’s just a washing machine, and it’s way too big for this break anyway. The whole stretch from Wednesday the 19th through to the 25th is a write-off, with only a few marginal windows.
Now, the real standouts come in the second week. Friday the 28th is looking like the best day of the whole run. The afternoon session has a 10 ft WSW groundswell with a 16-second period, and the wind is a light offshore from the north at just 6 mph. The energy is strong at 7102, and the conditions are clean. This is exceptional surf for expert surfers. The swell direction is a touch more west than the optimum SW, but with that light offshore wind and that long period, it’s going to be a ripper. Crowds are possible, but it’s a reef, so it’s self-selecting.
Monday the 31st is another one to circle. The morning session has a 8 ft SW groundswell with an 18-second period – that’s a very long period groundswell. The wind is glassy, dead calm from the ENE. Energy is strong at 4175. That’s about as clean as it gets. For the experienced surfer, this is a proper session. The long period will mean the waves are fat and powerful, with long waits between sets, but the paddle-out will be easy between sets.
So, if you’re an experienced surfer, the standouts are Monday the 17th morning, Friday the 28th afternoon, and Monday the 31st morning. The 31st is the true blue-ribbon session with glassy conditions and a solid SW groundswell.
Rusty.
Short Range ForecastSome drizzle, heaviest during Tue afternoon. Very mild (max 17°C on Mon afternoon, min 11°C on Mon night). Winds increasing (calm on Sat night, fresh winds from the NNE by Tue afternoon). | Days 5-7 Weather SummaryHeavy rain (total 21mm), heaviest during Fri afternoon. Very mild (max 15°C on Wed afternoon, min 11°C on Thu night). Winds increasing (light winds from the W on Thu afternoon, strong winds from the WNW by Fri morning). | ||||||||||||||||||
Sunday 16 | Monday 17 | Tuesday 18 | Wednesday 19 | Thursday 20 | Friday 21 | ||||||||||||||
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) | SW 14 | SW 14 | SW 14 | SW 14 | SW 16 | SW 16 | SW 15 | SW 17 | SW 16 | SW 15 | SW 15 | SW 15 | WSW 14 | SW 17 | WSW 13 | SW 16 | WSW 14 | WSW 17 | SW 16 |
Wave Graph | |||||||||||||||||||
3619 | 2927 | 2724 | 2371 | 3116 | 3353 | 2148 | 2414 | 1552 | 894 | 674 | 623 | 494 | 875 | 772 | 1764 | 3737 | 9705 | 7465 | |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | off | off | cross-off | off | off | cross-off | off | cross-off | cross-off | cross-off | cross-off | cross | cross-on | cross-on | cross-on | cross-on | cross | on | on |
High Tide | 1:40AM0.84m | 2:04PM0.95m | 2:14AM0.89m | 2:12PM0.91m | 2:48AM0.91m | 2:18PM0.88m | 3:24AM0.90m | 2:22PM0.85m | 4:04AM0.86m | 2:18PM0.84m | 4:52AM0.81m | 1:56PM0.83m | |||||||
Low Tide | 7:45AM0.30m | 8:14PM0.34m | 8:13AM0.36m | 8:28PM0.27m | 8:38AM0.44m | 8:47PM0.22m | 9:00AM0.52m | 9:07PM0.19m | 9:16AM0.62m | 9:28PM0.20m | 9:18AM0.70m | 9:47PM0.24m | |||||||
— | 6:52 | — | — | 6:50 | — | — | 6:48 | — | — | 6:48 | — | — | 6:47 | — | — | 6:46 | — | — | |
— | — | 5:30 | — | — | 5:31 | — | — | 5:32 | — | — | 5:34 | — | — | 5:35 | — | — | 5:35 | — | |
mm | — | — | — | — | — | — | — | — | 1 | 3 | 6 | 1 | 2 | — | 2 | 1 | 1 | 5 | — |
Temp °C | 13 | 13 | 13 | 13 | 16 | 17 | 15 | 15 | 13 | 13 | 14 | 15 | 13 | 14 | 13 | 12 | 13 | 12 | 11 |
Feels °C | 10 | 9 | 6 | 9 | 13 | 13 | 11 | 10 | 7 | 7 | 8 | 9 | 6 | 8 | 8 | 10 | 4 | 2 | 2 |
Swell 1 Height (m) Direction Period (s) | SW 14 | SW 14 | SW 14 | SW 14 | SW 16 | SW 16 | SW 15 | SW 17 | SW 16 | SW 15 | SW 15 | SW 15 | WSW 14 | W 9 | WSW 13 | SW 16 | WSW 14 | WSW 17 | — |
3619 | 2927 | 2724 | 2371 | 3116 | 3353 | 2148 | 2414 | 1552 | 894 | 674 | 623 | 493 | 473 | 772 | 1764 | 3737 | 9705 | — | |
Swell 2 Height (m) Direction Period (s) | SSW 16 | — | S 11 | S 12 | SSW 11 | SSW 22 | SW 19 | SE 6 | ESE 6 | E 4 | ESE 6 | SW 21 | SW 19 | SW 17 | SW 16 | W 10 | SW 18 | — | — |
259 | — | 367 | 324 | 40 | 308 | 808 | 5 | 4 | 1 | 8 | 116 | 494 | 875 | 560 | 460 | 2136 | — | — | |
Swell 3 Height (m) Direction Period (s) | — | — | — | — | SW 24 | — | SSW 10 | S 10 | S 9 | — | — | — | WSW 20 | WSW 13 | — | SW 19 | — | — | — |
— | — | — | — | 87 | — | 33 | 7 | 6 | — | — | — | 218 | 414 | — | 546 | — | — | — | |
Wind waves Height (m) Direction Period (s) | — | — | SSE 3 | — | — | SSE 11 | E 5 | NNE 3 | NNE 3 | N 4 | N 4 | NW 6 | W 8 | W 9 | W 8 | — | — | WSW 17 | SW 16 |
— | — | 7 | — | — | 117 | 20 | 6 | 8 | 30 | 59 | 245 | 439 | 550 | 284 | — | — | 8302 | 7465 | |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 0 | 0 | 127 | 0 | 0 | 9 | 0 | 28 | 28 | 28 | 295 | 216 | 287 | 87 | 87 | 20 | 87 | 287 | 310 |
Best forecast wave conditions in South Australia - East Coast | |||||||||||||||||||
Best forecast wave conditions in Australia | |||||||||||||||||||
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Information about the Cape Northumberland Surf forecast
The above surf forecast table for Cape Northumberland provides essential information for determining whether the surfing conditions will be good over the next 16 days. A general guide to surfing at Cape Northumberland can be found by selecting the local surf guide option on the grey menu. Our Cape Northumberland 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 (Cape Northumberland) 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 Cape Northumberland 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.
Cape Northumberland is 6 km (4 miles) from Allendale East. If you plan a holiday in South Australia - East Coast, look for hotels and other accommodation in Allendale East. Allendale East has rooms for a wide range of budgets as well as car hire and transport links.










