Surf Forecasts:
Nanakuli Blackrocks surf forecast from 19 Aug 2026:
- Best quality surf: Sunday 23 Aug, 2AM (local time) - 2.5ft (0.7m), 16s period, SW swell with offshore winds.
- Most powerful swell: Friday 21 Aug, 5AM (local time) - 3ft (0.9m), 17s period, SW swell with 414 kJ wave energy.
- Next surfable swell (1★+): Wednesday 19 Aug, 2AM (local time) - 2ft (0.6m), 12s period with S swell.
Best Forecast Surf Conditions for Nanakuli Blackrocks this week:
The surf forecast for Nanakuli Blackrocks over the next 16 days: The first swell (rated 1 star or higher) is forecast to arrive on Wednesday (Aug 19) at 2AM. The primary swell is predicted to be 0.6m and 12s period with a secondary swell of 0.4m and 10s. The wind is predicted to be offshore as the swell arrives.
The most powerful waves expected at Nanakuli Blackrocks in the next 16 days are 0.9m 17s and forecast to arrive on Friday (Aug 21) at 5AM. Winds are predicted to be glassy at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.9m 8s period and expected on Monday (Aug 24) at 8AM.
| Wave Type | Time (HST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 2AM (Wed 19th Aug) | 2ft (0.6m) 12s |
| Best Surf | 2AM (Sun 23rd Aug) | 2.5ft (0.7m) 16s |
| Most Powerful | 5AM (Fri 21st Aug) | 3ft (0.9m) 17s |
Table - best surf conditions forecast for Nanakuli Blackrocks over the next 16 days.
The Lowdown
Alright, let’s break it down for the inches and miles set.
Bottom line: the surf is going to be on the small side for a while, but if you’re patient, things get interesting in the second week.
We’re talking about Nanakuli Blackrocks. This place *rarely breaks*, so the fact it’s even on the radar is a little unusual. Water temp is normal for the season.
First chance to get wet is Wednesday, August 19th. Swell is a tiny 2ft, but the wind is light and offshore from the ENE. The swell is out of the SW with a very long period of 16 seconds – that’s pure groundswell. Combined energy is moderate (164). It’s surfable, but you won’t be hooting. The afternoon holds with a light breeze, energy picking up to 200.
Thursday, August 20th morning is glassy – dead calm with a 0 km/h wind. That’s a huge win. Swell bumps to 2ft, still a long 18-second period. Combined energy is moderate (316). This is your cleanest window early on. The afternoon stays clean with a light cross-off breeze.
Friday, August 21st is another beauty: glassy again in the morning, light southerly air, swell at 3ft from the SSW. Energy is solid (443). The afternoon stays glassy (436). This two-day stretch is small but beautifully clean.
Saturday, August 22nd and Sunday, August 23rd get windier. Saturday morning is okay with 3ft and a moderate offshore breeze (12-16 mph), but Sunday sees wind up to 19-22 mph. Swell stays tiny at 2ft. The surface gets lumpy.
Monday, August 24th is a bust. Strong offshore wind up to 28 mph makes paddling into these little 2ft waves a chore. Poor conditions.
There’s a lull, but things recover from Wednesday, August 26th. Swell direction shifts more southerly, and size hits 3ft with 18-second periods. Combined energy jumps to 560 – solid. The offshore breeze (16 mph) is manageable.
The real standout is Thursday, August 27th. Swell hits 3ft from the south, with a gentle 9 mph offshore breeze. Combined swell energy is 592 – the best of the whole outlook. Very clean and with proper shape. This is your best bet. The southerly groundswell at 16 seconds suits this spot.
After that, it fades. Saturday, August 29th is still okay at 2ft, but the wind picks up. By Sunday, August 30th, it’s dropping to 1-2ft. A small pulse comes through Monday, September 1st with 2ft and a 19-second period, but by Wednesday, September 3rd, the wind is roaring at 25 mph, ruining it.
So: the first week is for small-wave gear, but the glassy windows on Aug 20-21 are worth it. The main event is Thursday, August 27th – biggest and cleanest of the whole outlook. Mark your calendar.
Rusty.
Short Range ForecastMostly dry. Warm (max 27°C on Wed afternoon, min 24°C on Tue night). Wind will be generally light. | Days 5-7 Weather SummaryLight rain (total 3mm), mostly falling on Mon afternoon. Warm (max 28°C on Sat morning, min 25°C on Fri night). Winds increasing (calm on Fri night, strong winds from the ENE by Mon morning). | ||||||||||||||||||
Wednesday 19 | Thursday 20 | Friday 21 | Saturday 22 | Sunday 23 | Monday 24 | ||||||||||||||
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) | S 12 | SW 16 | SW 16 | SSW 16 | SW 18 | SW 17 | SSW 16 | SSW 17 | SSW 16 | SSW 16 | SSW 16 | SSW 16 | SW 16 | SSW 15 | SSW 15 | SSW 14 | SSW 14 | SSW 13 | SSW 13 |
Wave Graph  | |||||||||||||||||||
 kJ | 110 | 129 | 129 | 177 | 316 | 302 | 347 | 364 | 326 | 322 | 326 | 314 | 245 | 199 | 188 | 183 | 163 | 156 | 125 |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | off | off | off | off | glassy | cross-off | glassy | glassy | glassy | off | off | off | off | off | off | off | off | off | off |
High Tide | 9:54AM0.53m | 11:13AM0.55m | 12:17PM0.58m | 11:07PM0.20m | 1:05PM0.61m | 00:41AM0.22m | 1:43PM0.64m | 1:27AM0.24m | 2:17PM0.67m | 2:05AM0.28m | |||||||||
Low Tide | 1:22AM0.12m | 2:02AM0.13m | 3:07AM0.14m | 9:33PM0.20m | 9:13PM0.18m | 5:44AM0.11m | 9:21PM0.17m | 6:39AM0.09m | 9:34PM0.15m | ||||||||||
 |  | |  |  | | | | | | | | | | | | |  |  | |
 | — | 6:11 | — | — | 6:11 | — | — | 6:11 | — | — | 6:13 | — | — | 6:13 | — | — | 6:13 | — | — |
 | 7:00 | — | 6:59 | — | — | 6:59 | — | — | 6:58 | — | — | 6:57 | — | — | 6:55 | — | — | 6:54 | — |
mm | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 3 | 9 |
Temp °C | 25 | 26 | 27 | 26 | 26 | 27 | 26 | 27 | 27 | 26 | 28 | 28 | 26 | 27 | 28 | 26 | 27 | 27 | 26 |
Feels °C | 25 | 28 | 29 | 28 | 29 | 30 | 30 | 31 | 31 | 30 | 28 | 26 | 26 | 25 | 26 | 25 | 24 | 24 | 27 |
Swell 1 Height (m) Direction Period (s) | S 12 | E 8 | E 8 | E 8 | SW 18 | SW 17 | SSW 16 | SSW 17 | SSW 16 | SSW 16 | SSW 16 | ENE 7 | SW 16 | E 7 | SSW 15 | SSW 14 | SSW 14 | SSW 13 | SE 9 |
| kJ | 110 | 69 | 65 | 63 | 316 | 302 | 347 | 364 | 326 | 322 | 326 | 77 | 245 | 222 | 188 | 183 | 163 | 156 | 67 |
Swell 2 Height (m) Direction Period (s) | SSE 10 | SW 16 | SW 16 | SSW 16 | E 8 | E 8 | ENE 7 | W 11 | W 11 | ENE 7 | E 7 | WNW 11 | WNW 12 | SSW 15 | WNW 11 | NW 11 | E 10 | NW 11 | SSW 13 |
| kJ | 37 | 129 | 129 | 177 | 42 | 40 | 48 | 79 | 110 | 42 | 49 | 123 | 153 | 199 | 85 | 58 | 53 | 41 | 125 |
Swell 3 Height (m) Direction Period (s) | WNW 12 | SSE 10 | S 12 | S 12 | NNE 6 | NNE 6 | W 10 | E 7 | E 8 | W 10 | WNW 10 | SSW 16 | S 14 | SSE 13 | SSE 11 | S 13 | N 5 | SE 10 | SSW 17 |
| kJ | 48 | 35 | 71 | 45 | 13 | 13 | 52 | 27 | 29 | 74 | 108 | 314 | 106 | 141 | 25 | 87 | 9 | 36 | 92 |
Wind waves Height (m) Direction Period (s) | ENE 8 | ENE 7 | — | ENE 7 | — | — | — | — | — | — | ENE 7 | ENE 7 | E 7 | — | E 7 | E 7 | E 8 | E 8 | E 8 |
| kJ | 118 | 49 | — | 70 | — | — | — | — | — | — | 53 | 121 | 303 | — | 261 | 315 | 320 | 350 | 422 |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 7 | 0 | 8 | 169 | 168 | 169 | 17 | 7 |
Best forecast wave conditions in Oahu | |||||||||||||||||||
Best forecast wave conditions in United States | |||||||||||||||||||
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Information about the Nanakuli Blackrocks Surf forecast
The above surf forecast table for Nanakuli Blackrocks provides essential information for determining whether the surfing conditions will be good over the next 16 days. A general guide to surfing at Nanakuli Blackrocks can be found by selecting the local surf guide option on the grey menu. Our Nanakuli Blackrocks 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 (Nanakuli Blackrocks) 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 Nanakuli Blackrocks 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.
Nanakuli Blackrocks is 6 km (4 miles) from Makakilo City. If you plan a vacation in Oahu, look for hotels and other accommodation in Makakilo City. Makakilo City has rooms for a wide range of budgets as well as car hire and transport links.
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