Surf Forecasts:
Ammonias surf forecast from 15 Aug 2026:
- Best quality surf: Friday 21 Aug, 8AM (local time) - 2.5ft (0.7m), 17s period, SW swell with cross-offshore winds.
- Most powerful swell: Sunday 16 Aug, 8AM (local time) - 18ft (5.5m), 11s period, E swell with 6,268 kJ wave energy.
- Next surfable swell (1★+): Friday 21 Aug, 8AM (local time) - 2.5ft (0.7m), 17s period with SW swell.
Best Forecast Surf Conditions for Ammonias this week:
The surf forecast for Ammonias over the next 16 days: The first swell (rated 1 star or higher) is forecast to arrive on Friday (Aug 21) at 8AM. The primary swell is predicted to be 0.7m and 17s period with a secondary swell of 0.4m and 9s. Another secondary swell of 1.6m and 7s is also forecast. The wind is predicted to be cross-offshore as the swell arrives.
The most powerful waves expected at Ammonias in the next 16 days are 5.5m 11s and forecast to arrive on Sunday (Aug 16) at 8AM. Winds are predicted to be cross-shore at the time the swell arrives.
| Wave Type | Time (HST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 8AM (Fri 21st Aug) | 2.5ft (0.7m) 17s |
| Best Surf | 8AM (Fri 21st Aug) | 2.5ft (0.7m) 17s |
| Most Powerful | 8AM (Sun 16th Aug) | 18ft (5.5m) 11s |
Table - best surf conditions forecast for Ammonias over the next 16 days.
The Lowdown
Alright folks, Rusty here, checkin' in with the long-range picture for Ammonias.
We’ve got a bit of a rough patch to get through first. Honestly, the next few days are lookin' pretty grim. A lot of onshore and cross-shore winds are gonna mess up the surface, and the swell is either too small or blown out. From Friday the 14th through to about the 19th, it's a write-off with poor conditions. The combined energy is weak, in the hundreds (946) on the 14th, then shoots up with a big, messy windswell on the 16th hitting 5295, but it's a total washout. You'd be better off stayin' home.
The first real glimmer of hope comes on the morning of Thursday the 21st of August. A S-SE swell (optimum) is the call here, with a long period of 14 seconds, giving the waves some real shape. The swell height is only 5 ft, and the combined energy is a moderate 564. The wind is a gentle cross-shore, which will keep it clean. The water temp is 80°, which is normal for this time of year. It's a marginal call, but the best we've seen in a while. It's a reef break, so it loves that long period, but it's a fairly consistent spot, so you might get a few. Crowds are often here, so expect some company.
The better window really opens up on the 27th and 28th of August. On Thursday morning the 27th, we see a new E swell rolling in with a very long period of 18 seconds. The swell height is holding at 3 ft to 4 ft, and the combined energy jumps to a strong 1408. The wind is light and cross-onshore, just a light breeze, so the surface will have small ripples but should be rideable. Into Friday the 28th, the swell period drops slightly to 17 seconds, but the energy stays strong (1504). The wind gets even lighter, almost a whisper, with a slight air from the ESE at 3 mph. This is the standout window. That long period groundswell is going to wrap around the reef and give us some beautiful, lined-up waves, especially if you can find a take-off spot that's not too straight. It's a marginal call in the data, but the combination of that clean energy and light wind makes it the best on offer.
The forecast for the 29th looks like it's fading again, with a windswell mix and a drop in quality. So, if you're lookin' to paddle out, aim for the 21st, but really pencil in the 27th and 28th of August for the best chance at some clean, long-period groundswell at Ammonias.
Rusty, out.
Short Range ForecastHeavy rain (total 43mm), heaviest during Sun morning. Warm (max 27°C on Fri afternoon, min 25°C on Fri night). Winds decreasing (near gales from the ENE on Sun morning, light winds from the E by Sun night). | Days 5-7 Weather SummarySome drizzle, heaviest during Mon afternoon. Warm (max 26°C on Mon afternoon, min 24°C on Mon night). Wind will be generally light. | |||||||||||||||||||
Fri 14 | Saturday 15 | Sunday 16 | Monday 17 | Tuesday 18 | Wednesday 19 | Thursday 20 | ||||||||||||||
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) | S 14 | ENE 8 | ENE 8 | ENE 8 | ENE 9 | E 10 | E 9 | E 8 | ENE 8 | ENE 7 | S 14 | S 13 | ENE 6 | S 13 | ENE 7 | ENE 7 | ENE 7 | SSW 18 | SSW 17 | SW 16 |
Wave Graph  | ||||||||||||||||||||
 kJ | 496 | 526 | 801 | 1047 | 1785 | 5002 | 1590 | 686 | 368 | 305 | 229 | 165 | 119 | 114 | 136 | 113 | 151 | 207 | 195 | 278 |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross | cross | cross | cross | cross | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on | cross | cross-on | cross | cross | cross-on | cross | cross-off |
High Tide | 5:03PM0.59m | 5:36AM0.41m | 5:29PM0.52m | 6:32AM0.43m | 5:50PM0.44m | 7:34AM0.46m | 6:01PM0.36m | 8:46AM0.48m | 5:31PM0.30m | 10:06AM0.50m | 11:20AM0.53m | |||||||||
Low Tide | 11:35PM0.07m | 11:06AM0.12m | 00:00AM0.06m | 12:01PM0.20m | 00:26AM0.06m | 1:11PM0.26m | 00:55AM0.06m | 3:13PM0.30m | 1:28AM0.08m | 2:14AM0.09m | 3:21AM0.10m | |||||||||
 |  |  | |  |  |  |  | | |  |  | | | | | | | | | |
 | — | — | 6:15 | — | — | 6:15 | — | — | 6:15 | — | — | 6:16 | — | — | 6:16 | — | — | 6:16 | — | — |
 | 7:08 | — | — | 7:07 | — | — | 7:07 | — | — | 7:06 | — | — | 7:06 | — | — | 7:05 | — | — | 7:04 | — |
mm | — | — | 1 | 2 | 7 | 15 | 9 | 7 | 2 | 1 | — | — | — | — | — | — | — | — | — | 3 |
Temp °C | 27 | 25 | 26 | 26 | 25 | 25 | 26 | 26 | 26 | 26 | 25 | 25 | 26 | 25 | 25 | 26 | 24 | 26 | 26 | 25 |
Feels °C | 26 | 25 | 25 | 25 | 24 | 20 | 25 | 26 | 27 | 27 | 25 | 25 | 25 | 26 | 26 | 26 | 24 | 27 | 27 | 26 |
Swell 1 Height (m) Direction Period (s) | S 14 | S 14 | S 13 | S 13 | S 13 | S 12 | S 13 | ENE 8 | S 14 | S 12 | S 14 | S 13 | S 13 | S 13 | SSE 10 | S 12 | SW 16 | SSW 18 | SSW 17 | SW 16 |
| kJ | 496 | 394 | 280 | 219 | 222 | 150 | 157 | 541 | 334 | 150 | 229 | 165 | 119 | 114 | 63 | 69 | 130 | 207 | 195 | 278 |
Swell 2 Height (m) Direction Period (s) | SE 12 | SE 13 | E 12 | S 16 | S 18 | S 17 | S 16 | SE 7 | SSE 6 | SSE 6 | SE 11 | SE 9 | SE 10 | SE 10 | S 12 | SSW 16 | SSE 9 | SE 9 | SSE 9 | SSE 9 |
| kJ | 21 | 27 | 76 | 46 | 98 | 143 | 181 | 140 | 50 | 35 | 30 | 21 | 47 | 46 | 69 | 103 | 31 | 22 | 32 | 32 |
Swell 3 Height (m) Direction Period (s) | W 11 | W 11 | W 13 | SE 12 | WNW 12 | W 12 | SE 12 | S 14 | SE 11 | S 15 | SE 6 | SW 17 | SW 18 | WNW 12 | SW 16 | SE 9 | S 12 | S 11 | S 11 | S 11 |
| kJ | 22 | 21 | 29 | 24 | 49 | 25 | 35 | 289 | 30 | 150 | 9 | 76 | 80 | 28 | 129 | 22 | 44 | 40 | 23 | 23 |
Wind waves Height (m) Direction Period (s) | ENE 8 | ENE 8 | ENE 8 | ENE 8 | ENE 9 | E 10 | E 9 | E 8 | ENE 8 | ENE 7 | ENE 7 | ENE 6 | ENE 6 | ENE 6 | ENE 7 | ENE 7 | ENE 7 | ENE 7 | ENE 7 | ENE 7 |
| kJ | 429 | 526 | 801 | 1047 | 1785 | 5002 | 1590 | 686 | 368 | 305 | 227 | 140 | 113 | 97 | 136 | 113 | 151 | 173 | 151 | 178 |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 31 | 31 | 31 | 31 | 31 | 299 | 133 | 126 | 126 | 126 | 31 | 31 | 31 | 16 | 31 | 16 | 16 | 31 | 15 | 14 |
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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