Surf Forecasts:
Fortress surf forecast from 17 Aug 2026:
- Best quality surf: Tuesday 18 Aug, 5AM (local time) - 3.5ft (1.0m), 6s period, SSE swell with cross-offshore winds.
- Most powerful swell: Monday 17 Aug, 5PM (local time) - 4.5ft (1.3m), 6s period, SSE swell with 121 kJ wave energy.
- Next surfable swell (1★+): Tuesday 18 Aug, 5AM (local time) - 3.5ft (1.0m), 6s period with SSE swell.
Best Forecast Surf Conditions for Fortress this week:
The surf forecast for Fortress over the next 16 days: The first swell (rated 1 star or higher) is forecast to arrive on Tuesday (Aug 18) at 5AM. The primary swell is predicted to be 1.0m and 6s period with a secondary swell of 0.1m and 14s. Another secondary swell of 0.2m and 2s is also forecast. The wind is predicted to be cross-offshore as the swell arrives.
The most powerful waves expected at Fortress in the next 16 days are 1.3m 6s and forecast to arrive on Monday (Aug 17) at 5PM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.4m 4s period and expected on Thursday (Aug 20) at 11AM.
| Wave Type | Time (EDT) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 5AM (Tue 18th Aug) | 3.5ft (1.0m) 6s |
| Best Surf | 5AM (Tue 18th Aug) | 3.5ft (1.0m) 6s |
| Most Powerful | 5PM (Mon 17th Aug) | 4.5ft (1.3m) 6s |
Table - best surf conditions forecast for Fortress over the next 16 days.
The Lowdown
Alright folks, it’s Rusty here. Let’s be honest with each other. The next week to ten days are looking pretty flat and pretty grim. That first week, honestly, you can almost forget it. Just about nothing on offer.
It’s not until the 25th of August that things start to stir a little. Fortress (Big Island) will see a pulse of windswell from the south pushing the surf to around 4ft to 5ft. It's not going to be world-class, but there's some energy in the water and the morning of the 25th looks workable with a moderate offshore breeze. The period is short, around 6 seconds, and the energy is moderate, but it's the first real sign of life. Tuesday morning would be your pick here, as conditions nudge closer to clean.
Water temp is 72.5°, which is about average for this time of year, nothing wild going on there.
After that, the real standout rears its head on the 28th of August. There's a bigger pulse of swell coming, with surf pushing past 4ft and energy jumping up strongly (652). This is a long period groundswell, 13 seconds, and it comes from the southeast. This is a much more powerful, better-period swell than what we’ve seen all window. But, and it’s a big but, the wind is going to be honking onshore from the ENE at 25 mph. This makes it a messy, lumpy mess, and honestly not the best for clean surfing. It’ll be big for Fortress but probably more interesting for the kite crew than the paddle surfers, given the onshore mayhem. If the wind eases, it would be all-time, but as it stands, it's a raw and powerful ocean.
The rest of the window is a write-off. We’re back down to knee-high baby waves for the final days of August, even with a bit of swell in the water. Blame the onshore wind ruining what little is there.
So, there you have it. The surf is scarce and the good windows are small. The 25th is your best bet for a quiet, half-decent wave with clean conditions. The 28th has raw power, but you’ll have to earn it. Otherwise, save your energy. A long, flat spell, but that’s the nature of the sea around here sometimes. It’ll turn around.
Stay salty.
Short Range ForecastLight rain (total 4mm), mostly falling on Mon morning. Warm (max 26°C on Tue afternoon, min 21°C on Mon morning). Winds decreasing (fresh winds from the SSE on Mon morning, light winds from the NNE by Wed night). | Days 4-6 Weather SummaryHeavy rain (total 21mm), heaviest during Fri afternoon. Warm (max 24°C on Thu morning, min 19°C on Fri night). Winds increasing (calm on Thu morning, fresh winds from the NE by Fri night). | ||||||||||||||||||||
Monday 17 | Tuesday 18 | Wednesday 19 | Thursday 20 | Friday 21 | Saturday 22 | Sunday 23 | |||||||||||||||
AM | 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) | SSE 6 | SSE 6 | SSE 6 | SSE 7 | SSE 7 | SSE 7 | SE 6 | SE 6 | SE 6 | ESE 7 | SE 7 | SE 7 | SE 8 | SE 8 | SE 8 | E 4 | ESE 5 | ESE 6 | E 6 | ESE 6 | SE 12 |
Wave Graph  | |||||||||||||||||||||
 kJ | 114 | 121 | 82 | 72 | 54 | 59 | 40 | 31 | 16 | 21 | 12 | 12 | 18 | 18 | 17 | 19 | 64 | 86 | 85 | 33 | 22 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | cross-on | cross | cross-off | cross-off | off | on | cross | cross-off | cross | cross | glassy | cross-on | cross | cross-on | cross-on | on | cross-on | on | cross-off | cross-off |
High Tide | 11:52AM0.93m | 11:48PM0.74m | 12:35PM0.87m | 00:23AM0.67m | 1:23PM0.81m | 1:03AM0.61m | 2:23PM0.77m | 1:53AM0.57m | 3:43PM0.74m | 3:07AM0.55m | 4:56PM0.75m | 5:09AM0.57m | 5:52PM0.77m | ||||||||
Low Tide | 5:39PM0.12m | 5:30AM0.09m | 6:28PM0.20m | 6:07AM0.15m | 7:27PM0.26m | 6:51AM0.20m | 8:51PM0.30m | 7:45AM0.24m | 10:13PM0.29m | 8:54AM0.27m | 11:11PM0.26m | 10:13AM0.26m | 11:56PM0.22m | ||||||||
 |  |  | | |  | | | |  |  |  | |  |  | | | |  |  | | |
 | 5:58 | — | — | 6:00 | — | — | 6:01 | — | — | 6:01 | — | — | 6:03 | — | — | 6:03 | — | — | 6:05 | — | — |
 | — | 7:44 | — | — | 7:42 | — | — | 7:40 | — | — | 7:38 | — | — | 7:37 | — | — | 7:36 | — | — | 7:35 | — |
mm | 4 | — | — | — | — | — | — | — | — | — | 1 | 4 | 1 | 13 | 2 | — | — | — | 8 | 3 | 16 |
Temp °C | 23 | 25 | 23 | 22 | 26 | 26 | 22 | 26 | 26 | 24 | 24 | 23 | 20 | 21 | 19 | 20 | 21 | 22 | 21 | 22 | 21 |
Feels °C | 21 | 29 | 24 | 24 | 26 | 26 | 24 | 27 | 25 | 27 | 26 | 25 | 19 | 22 | 16 | 20 | 22 | 23 | 22 | 25 | 22 |
Swell 1 Height (m) Direction Period (s) | — | SSE 6 | SSE 6 | SSE 7 | SSE 7 | SSE 7 | SE 6 | SE 6 | SE 6 | S 6 | SE 7 | SE 7 | SE 8 | SE 8 | SE 8 | SE 13 | SE 13 | SE 13 | E 6 | ESE 6 | SSE 5 |
| kJ | — | 121 | 82 | 72 | 54 | 59 | 40 | 31 | 16 | 9 | 12 | 12 | 18 | 18 | 17 | 7 | 7 | 7 | 85 | 33 | 9 |
Swell 2 Height (m) Direction Period (s) | — | — | — | E 4 | SE 8 | SSE 11 | SE 10 | SE 9 | SE 9 | ESE 7 | SE 9 | ESE 9 | S 5 | S 5 | — | — | SE 9 | SE 9 | ESE 12 | S 5 | E 5 |
| kJ | — | — | — | 3 | 25 | 12 | 4 | 14 | 12 | 21 | 12 | 8 | 2 | 2 | — | — | 3 | 3 | 15 | 5 | 9 |
Swell 3 Height (m) Direction Period (s) | — | — | S 14 | SE 13 | SE 12 | SSE 11 | — | — | SW 6 | SE 9 | ESE 9 | S 5 | SE 5 | SE 14 | SE 14 | S 9 | — | S 5 | SE 8 | ESE 12 | SE 12 |
| kJ | — | — | 4 | 7 | 6 | 12 | — | — | 1 | 3 | 8 | 2 | 1 | 8 | 8 | 2 | — | 1 | 3 | 14 | 22 |
Wind waves Height (m) Direction Period (s) | SSE 6 | — | NNE 2 | — | — | — | — | — | S 3 | SW 4 | SSW 5 | SSW 3 | NE 4 | E 4 | E 4 | E 4 | ESE 5 | ESE 6 | — | — | S 5 |
| kJ | 114 | — | 1 | — | — | — | — | — | 2 | 7 | 9 | 2 | 13 | 7 | 12 | 19 | 64 | 86 | — | — | 21 |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 129 | 5 | 15 | 0 | 9 | 0 | 129 | 178 | 15 | 2 | 1117 | 15 | 801 | 404 | 219 | 155 | 451 | 36 | 49 | 0 | 0 |
Best forecast wave conditions in Long Island New York | |||||||||||||||||||||
Best forecast wave conditions in United States | |||||||||||||||||||||
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Information about the Fortress Surf forecast
The above surf forecast table for Fortress provides essential information for determining whether the surfing conditions will be good over the next 16 days. A general guide to surfing at Fortress can be found by selecting the local surf guide option on the grey menu. Our Fortress 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 (Fortress) 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 Fortress 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.
Fortress is 39 km (24 miles) from New London. If you plan a vacation in Long Island New York, look for hotels and other accommodation in New London. New London has rooms for a wide range of budgets as well as car hire and transport links.
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