Surf Forecasts:
Ammonias surf forecast from 14 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 1.6m 6s 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
Alright, Rusty here. Let’s break it down.
First up, Monday the 14th through Thursday the 17th are flat and messy – not worth paddling out. Water temp is 80°, pretty normal for this time of year.
Wednesday the 16th morning shows a small swell at 3ft from the SW with an 18-second period, and the combined energy is moderate at 608. Wind’s cross-shore, so it’s lumpy. Not a goer.
Friday the 18th sees a bit more size, 3ft from the SSW with a 16-second period and strong energy at 1018. But the wind is cross-onshore, making it choppy. Marginal.
The first real highlight comes on Friday the 25th afternoon at Ammonias (reef). Swell is 3ft from the SSW, 15-second period, and the wind goes cross-offshore from the NNE at 9 mph. Clean, lined-up surf with moderate energy (566). This is the first proper session window.
Saturday the 26th and Sunday the 27th keep it clean with light cross-offshore winds at 6 mph. Swell stays at 3ft to 3ft from the SSW, periods of 14 to 16 seconds. Moderate energy (462 to 419). Crowds are often, so expect some company.
The absolute best is Monday the 28th. Glassy conditions all day – calm in the morning, then light north wind in the afternoon. Swell is 3ft to 3ft from the SSW with a long 18-second period. Combined energy is strong (647). On a reef break, that long-period groundswell will produce some beautiful, well-shaped waves. This is the standout.
Tuesday the 29th afternoon keeps the clean run going with cross-offshore winds and 3ft SSW swell at 16 seconds. Strong energy at 768. Another solid day.
First week is a bust. From the 25th to the 29th, it’s on. Monday the 28th is the one to circle – glassy, clean, and quality.
Rusty.
Short Range ForecastLight rain (total 3mm), mostly falling on Wed night. Warm (max 27°C on Tue afternoon, min 24°C on Mon night). Wind will be generally light. | Days 4-6 Weather SummaryHeavy rain (total 38mm), heaviest during Fri morning. Warm (max 27°C on Fri morning, min 25°C on Thu night). Wind will be generally light. | ||||||||||||||||||||
Monday 14 | Tuesday 15 | Wednesday 16 | Thursday 17 | Friday 18 | Saturday 19 | Sunday 20 | |||||||||||||||
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) | SW 14 | SW 22 | 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 | ENE 8 | SSW 16 | ENE 8 | SSW 15 | SSW 15 | SSW 14 |
Wave Graph  | |||||||||||||||||||||
 kJ | 49 | 227 | 224 | 392 | 384 | 465 | 449 | 541 | 360 | 258 | 423 | 651 | 608 | 566 | 532 | 373 | 382 | 383 | 500 | 468 | 449 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross | cross | cross | cross-on | cross | cross | cross | cross | cross | cross | cross | cross | cross-on | cross | cross | cross-on | cross-on | cross-on | cross-on | cross | cross |
High Tide | 4:55PM0.35m | 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 | 12:08PM0.22m | 11:14PM0.05m | 1:23PM0.26m | 11:40PM0.08m | 00:11AM0.10m | 00:58AM0.13m | 9:18PM0.19m | 8:14PM0.19m | 8:09PM0.18m | ||||||||||||
 | |  |  | | | | |  |  | | | | | | | | | | |  | |
 | 6:22 | — | — | 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 | 2 | 10 | 9 | 4 | 3 | 4 | 2 | 3 | 2 | — | — |
Temp °C | 26 | 26 | 25 | 26 | 27 | 26 | 26 | 27 | 25 | 26 | 26 | 25 | 27 | 27 | 26 | 26 | 27 | 25 | 26 | 26 | 25 |
Feels °C | 26 | 26 | 25 | 27 | 28 | 28 | 26 | 28 | 26 | 27 | 26 | 25 | 27 | 27 | 27 | 26 | 27 | 25 | 26 | 26 | 26 |
Swell 1 Height (m) Direction Period (s) | NE 8 | NE 8 | SW 21 | 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 |
| kJ | 102 | 82 | 224 | 392 | 384 | 465 | 449 | 541 | 360 | 258 | 326 | 651 | 608 | 566 | 532 | 367 | 382 | 257 | 500 | 468 | 449 |
Swell 2 Height (m) Direction Period (s) | SW 14 | SW 22 | SSW 13 | NNE 8 | SW 12 | E 11 | E 11 | E 10 | E 10 | E 10 | SSW 19 | SSE 10 | SSE 10 | S 21 | SSE 7 | SSE 8 | SSE 8 | SE 8 | SSE 8 | SSE 8 | SSE 6 |
| kJ | 49 | 227 | 67 | 23 | 38 | 39 | 36 | 50 | 75 | 98 | 214 | 10 | 9 | 36 | 36 | 55 | 54 | 62 | 24 | 24 | 16 |
Swell 3 Height (m) Direction Period (s) | SE 8 | SW 14 | SE 8 | NE 8 | E 12 | SW 12 | SW 11 | SW 11 | SSW 21 | SSW 19 | SW 10 | WSW 9 | W 9 | W 9 | S 20 | S 18 | S 18 | SSW 13 | W 13 | W 12 | W 12 |
| kJ | 17 | 47 | 15 | 23 | 26 | 37 | 33 | 43 | 86 | 214 | 15 | 8 | 6 | 6 | 67 | 162 | 160 | 102 | 13 | 12 | 11 |
Wind waves Height (m) Direction Period (s) | ENE 4 | ENE 5 | NE 8 | ENE 6 | NE 8 | ENE 5 | ENE 6 | NE 6 | ENE 6 | NE 6 | ENE 7 | ENE 9 | ENE 8 | ENE 8 | ENE 7 | ENE 8 | ENE 8 | ENE 8 | E 8 | ENE 7 | ENE 7 |
| kJ | 18 | 25 | 154 | 58 | 173 | 78 | 90 | 105 | 145 | 207 | 423 | 576 | 460 | 416 | 362 | 373 | 365 | 383 | 374 | 326 | 327 |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 31 | 31 | 16 | 31 | 31 | 16 | 16 | 31 | 14 | 31 | 31 | 16 | 33 | 118 | 16 | 33 | 33 | 33 | 33 | 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
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