
Surf Forecasts:
Ammonias surf forecast from 15 Sep 2026:
- Most powerful swell: Thursday 17 Sep, 11PM (local time) - 3.5ft (1.0m), 18s period, SSW swell with 659 kJ wave energy.
Best Forecast Surf Conditions for Ammonias this week:
The most powerful waves expected at Ammonias in the next 16 days are 1.0m 18s and forecast to arrive on Thursday (Sep 17) at 11PM. Winds are predicted to be cross-shore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.7m 7s period and expected on Thursday (Sep 17) at 11AM.
| Wave Type | Time (HST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | - | - |
| Best Surf | - | - |
| Most Powerful | 11PM (Thu 17th Sep) | 3.5ft (1.0m) 18s |
Table - best surf conditions forecast for Ammonias over the next 16 days.
The Lowdown
G’day, Rusty here. Let’s be straight – it’s a bit of a flat spell for Ammonias. This is a reef setup, exposed to the swell, and the optimum direction is SSE. Over the next couple of weeks, there’s not much to get excited about. Most days are either marginal or just plain poor. The winds are mostly cross or cross-on, and the water temp is about average for the time of year.
We’ll kick off on Tuesday the 15th of September with some waist-high swell from the SW, around 2ft, and a very long period of 20 seconds. That period is a good sign for a reef like this – it’ll push in with real shape and energy. The combined swell energy is moderate (507). But the trouble is the wind: a moderate cross-breeze at 12 mph from the ENE, keeping things a bit lumpy with a cross-chop. It’s marginal, and the tide could muck it up. Not a standout, but if you’re desperate, you might get a few.
Wednesday the 16th is much the same – 3ft from the SW in the morning, period 18 seconds, moderate cross-energy (518). Wind is still ENE at 12 mph, cross. The afternoon bumps up to 3ft from the SSW, still a long period of 18 seconds, with stronger combined energy (634). Still cross-wind, still marginal. The best of the whole run? Honestly, that’s as good as it gets until the very end.
You have to wait. Thursday the 17th afternoon sees a jump in height to 7ft from the ENE but with a shocking period of only 7 seconds – that’s windswell junk, crumbly and weak. Combined energy is 960, moderate, but the score is zero. Friday the 18th morning has 3ft from the SSW at 17 seconds, with combined energy of 1125 – that’s moderate to strong – but the wind is cross-on and choppy. Afternoon is cross-shore but still marginal.
From Saturday the 19th right through to Monday the 22nd, it’s a mix of 3ft to 5ft swell, mostly short period windswell (8 to 15 seconds). Winds are cross or cross-on, and it’s all scoring zero or one. Not worth paddling out. The energy is moderate to strong, but the quality just isn’t there.
Now, hold tight for the last few days. Tuesday the 29th of September afternoon brings a small 3ft from the SSW at 16 seconds, with combined energy 380 – weak. But check this: the wind goes cross-off at 16 mph from the NE. That’s clean. The reef will be tidy. It’s still marginal with the tide, but that’s the cleanest window. Wednesday the 30th of September morning has 2ft from the SSW at 15 seconds (284 energy) with a cross-off breeze from the NNE at 12 mph. Glassy-ish, clean. For a reef like Ammonias, that little pulse on the 29th afternoon and the 30th morning is the pick – small but clean. Crowds are often here, so you might have company.
If you’re a beginner, nothing here gets over 5ft until the 7ft windswell of the 17th, which is poor quality and short period. The bigger stuff in the 5ft to 6ft range on the 22nd to 24th is also short period and messy – better for kite surfing than paddling.
Overall, this 16-day outlook is lean. The best true standout is the small clean window on Tuesday the 29th afternoon and Wednesday the 30th morning. Otherwise, it’s a waiting game.
Rusty.
Short Range ForecastLight rain (total 7mm), mostly falling on Tue night. Warm (max 27°C on Wed morning, min 24°C on Mon night). Wind will be generally light. | Days 5-7 Weather SummaryHeavy rain (total 23mm), heaviest during Thu night. Warm (max 27°C on Fri morning, min 25°C on Thu night). Wind will be generally light. | ||||||||||||||||||
Tuesday 15 | Wednesday 16 | Thursday 17 | Friday 18 | Saturday 19 | Sunday 20 | ||||||||||||||
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 21 | SW 20 | SW 19 | SSW 19 | SW 18 | SSW 18 | SSW 17 | SW 16 | ENE 7 | SSW 18 | SSW 17 | SSW 16 | SSW 16 | SSW 15 | SSW 16 | ENE 8 | SSW 15 | SSW 15 | SSW 14 |
Wave Graph | |||||||||||||||||||
224 | 392 | 384 | 465 | 449 | 541 | 443 | 258 | 405 | 651 | 608 | 566 | 532 | 367 | 382 | 350 | 500 | 468 | 449 | |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross | cross | cross | cross | cross | cross | cross | cross | cross | cross | cross-on | cross | cross | cross-on | cross | cross-on | cross-on | cross | cross |
High Tide | 6:45AM0.55m | 4:58PM0.30m | 7:44AM0.54m | 9:00AM0.53m | 10:23AM0.54m | 9:42PM0.19m | 11:33AM0.55m | 11:46PM0.22m | 12:24PM0.57m | 00:31AM0.26m | |||||||||
Low Tide | 11:14PM0.05m | 1:23PM0.26m | 11:40PM0.08m | 00:11AM0.10m | 00:58AM0.13m | 9:18PM0.19m | 8:14PM0.19m | 8:09PM0.18m | |||||||||||
— | 6:24 | — | — | 6:24 | — | — | 6:24 | — | — | 6:24 | — | — | 6:24 | — | — | 6:24 | — | — | |
6:40 | — | 6:39 | — | — | 6:38 | — | — | 6:37 | — | — | 6:37 | — | — | 6:36 | — | — | 6:35 | — | |
mm | — | — | — | 3 | — | — | 1 | 1 | 2 | 8 | 8 | 2 | 3 | 1 | — | 1 | — | — | 1 |
Temp °C | 25 | 26 | 26 | 26 | 27 | 27 | 26 | 26 | 26 | 26 | 27 | 27 | 25 | 26 | 27 | 25 | 26 | 27 | 25 |
Feels °C | 26 | 27 | 27 | 29 | 28 | 28 | 27 | 27 | 26 | 27 | 27 | 27 | 25 | 26 | 27 | 26 | 26 | 27 | 25 |
Swell 1 Height (m) Direction Period (s) | NE 8 | SW 20 | SW 19 | SSW 19 | SW 18 | SSW 18 | SSW 17 | SW 16 | SSW 16 | SSW 18 | SSW 17 | SSW 16 | SSW 16 | SSW 15 | SSW 16 | S 16 | SSW 15 | SSW 15 | SSW 14 |
69 | 392 | 384 | 465 | 449 | 541 | 443 | 258 | 326 | 651 | 608 | 566 | 532 | 367 | 382 | 257 | 500 | 468 | 449 | |
Swell 2 Height (m) Direction Period (s) | SW 21 | NNE 8 | NNE 8 | E 11 | E 11 | E 10 | E 10 | E 10 | SSW 19 | SSE 10 | SSE 10 | SE 8 | SE 7 | SE 7 | SSE 7 | SSE 7 | SE 8 | SE 8 | W 12 |
224 | 34 | 41 | 39 | 36 | 50 | 75 | 96 | 214 | 10 | 9 | 16 | 39 | 51 | 33 | 29 | 17 | 17 | 11 | |
Swell 3 Height (m) Direction Period (s) | SSW 13 | SW 12 | SW 12 | SW 12 | SW 11 | SW 11 | SW 11 | SSW 19 | SW 10 | WSW 9 | S 20 | S 21 | S 20 | S 18 | S 18 | SSW 13 | N 11 | W 12 | NNW 10 |
67 | 40 | 38 | 37 | 33 | 43 | 30 | 214 | 15 | 8 | 33 | 36 | 67 | 162 | 160 | 158 | 2 | 11 | 11 | |
Wind waves Height (m) Direction Period (s) | ENE 4 | ENE 8 | ENE 5 | NE 8 | NE 7 | NE 7 | NE 6 | ENE 7 | ENE 7 | ENE 8 | ENE 8 | ENE 8 | ENE 8 | ENE 8 | ENE 8 | ENE 8 | E 8 | ENE 7 | ENE 7 |
15 | 75 | 38 | 129 | 91 | 127 | 147 | 237 | 405 | 554 | 475 | 404 | 383 | 302 | 341 | 350 | 365 | 317 | 394 | |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 16 | 31 | 31 | 16 | 16 | 16 | 14 | 31 | 31 | 16 | 33 | 16 | 16 | 31 | 46 | 16 | 31 | 16 | 16 |
Best forecast wave conditions in Kaua'i | |||||||||||||||||||
Best forecast wave conditions in United States | |||||||||||||||||||
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Information about the Ammonias Surf forecast
The above surf forecast table for Ammonias provides essential information for determining whether the surfing conditions will be good over the next 16 days. A general guide to surfing at Ammonias can be found by selecting the local surf guide option on the grey menu. Our Ammonias 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 (Ammonias) 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 Ammonias 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.
Are you planning a vacation in Kaua'i? If you are looking for accommodation near Ammonias, camping, hotels and condos and appartments in Kaua'i, consider staying in Nawiliwili which is 2 km (1 miles) away. Alternatively, find information about places to stay and car hire in Lihue - Kauai which is 3 km (2 miles) away










