Surf Forecasts:
Ammonias surf forecast from 16 Aug 2026:
- Most powerful swell: Sunday 16 Aug, 8AM (local time) - 16ft (5.0m), 10s period, E swell with 5,417 kJ wave energy.
Best Forecast Surf Conditions for Ammonias this week:
The most powerful waves expected at Ammonias in the next 16 days are 5.0m 10s and forecast to arrive on Sunday (Aug 16) at 8AM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.9m 7s period and expected on Friday (Aug 21) at 5AM.
| Wave Type | Time (HST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | - | - |
| Best Surf | - | - |
| Most Powerful | 8AM (Sun 16th Aug) | 16ft (5.0m) 10s |
Table - best surf conditions forecast for Ammonias over the next 16 days.
The Lowdown
Alright, Rusty here again, but this time in feet and miles per hour. Let’s check the run.
The first week is pretty rough. We’ve got a big 15ft swell coming in on Sunday the 16th, but it’s howling with a 28 mph cross-onshore wind. The energy is a crazy 4560, but it’s just a messy, gnarly paddle out – more for the kite crew. The following days are all cross-shore winds and choppy conditions, not much to get excited about.
Things start to look a bit better around Tuesday the 25th, but it’s still marginal. The real chance comes later. The standout is Ammonias (Ammonias). This reef break is our best bet. The peak of the window looks like Saturday the 29th morning. You’ll see a solid 8ft of swell from the East, with about a 9-second period. The combined energy is a strong 1640. The wind is cross-shore, so not perfect, but it’s rideable. It’s a fairly consistent spot, and crowds are possible, so get there early. The swell size at 8ft is for intermediates and above; beginners should sit this one out.
The water temp is about what you’d expect for this time of year.
The swell keeps coming through the end of the month, with waves in the 6 to 10ft range, but the wind stays on it, so don’t expect it to be silky smooth.
Best advice: aim for Saturday the 29th morning at Ammonias. It’s not a perfect day, but it’s the one with the most going for it.
Rusty
Short Range ForecastHeavy rain (total 66mm), heaviest during Sun morning. Warm (max 26°C on Sun afternoon, min 24°C on Mon night). Winds decreasing (strong winds from the ENE on Sun morning, light winds from the ESE by Sun night). | Days 5-7 Weather SummaryMostly dry. Warm (max 26°C on Wed morning, min 24°C on Tue night). Wind will be generally light. | ||||||||||||||||||
Sunday 16 | Monday 17 | Tuesday 18 | Wednesday 19 | Thursday 20 | Friday 21 | ||||||||||||||
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) | ENE 10 | E 10 | E 9 | ENE 8 | ENE 8 | ENE 7 | S 14 | ENE 7 | ENE 6 | S 13 | E 9 | ENE 7 | SW 16 | SSW 18 | SSW 17 | SW 16 | SSW 17 | SW 16 | SSW 16 |
Wave Graph  | |||||||||||||||||||
 kJ | 2924 | 4262 | 1744 | 606 | 378 | 330 | 232 | 165 | 125 | 112 | 154 | 107 | 130 | 209 | 197 | 278 | 255 | 261 | 322 |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on | cross | cross-on | cross-on | cross | cross | cross-on | cross | cross | cross-on | on | cross |
High Tide | 6:32AM0.43m | 5:50PM0.44m | 7:34AM0.46m | 6:01PM0.36m | 8:46AM0.48m | 5:31PM0.30m | 10:06AM0.50m | 11:20AM0.53m | 12:20PM0.56m | 11:30PM0.20m | |||||||||
Low Tide | 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 | 9:24PM0.19m | |||||||||
 |  | |  | |  |  | | | |  | | | | |  | | | | |
 | — | 6:15 | — | — | 6:15 | — | — | 6:16 | — | — | 6:16 | — | — | 6:16 | — | — | 6:16 | — | — |
 | 7:07 | — | 7:07 | — | — | 7:06 | — | — | 7:06 | — | — | 7:05 | — | — | 7:04 | — | — | 7:02 | — |
mm | 7 | 34 | 18 | 5 | 2 | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
Temp °C | 25 | 25 | 26 | 26 | 26 | 26 | 25 | 25 | 26 | 25 | 26 | 26 | 25 | 26 | 26 | 25 | 26 | 26 | 26 |
Feels °C | 23 | 21 | 27 | 26 | 28 | 27 | 26 | 25 | 26 | 26 | 27 | 26 | 26 | 27 | 27 | 27 | 28 | 28 | 29 |
Swell 1 Height (m) Direction Period (s) | S 13 | S 13 | S 13 | ENE 8 | S 14 | S 6 | S 14 | S 13 | S 13 | S 13 | NE 7 | S 12 | SW 16 | E 7 | NE 6 | NE 7 | ENE 8 | ENE 8 | NE 7 |
| kJ | 173 | 156 | 157 | 606 | 334 | 40 | 232 | 165 | 121 | 112 | 23 | 69 | 130 | 48 | 33 | 45 | 98 | 98 | 79 |
Swell 2 Height (m) Direction Period (s) | S 18 | S 17 | S 16 | SSE 7 | SE 7 | S 13 | SSW 6 | SE 10 | SE 9 | SE 8 | S 12 | SSW 16 | SSE 9 | SSW 18 | SSW 17 | SW 16 | SSW 17 | SW 16 | SSW 16 |
| kJ | 98 | 142 | 181 | 220 | 65 | 155 | 12 | 46 | 41 | 31 | 69 | 103 | 33 | 209 | 197 | 278 | 255 | 261 | 322 |
Swell 3 Height (m) Direction Period (s) | WNW 12 | W 12 | WNW 11 | S 14 | S 7 | SE 6 | SE 11 | SW 17 | SW 18 | WNW 12 | SW 16 | SSE 9 | S 12 | SSE 10 | E 7 | E 8 | SE 9 | SE 9 | SE 9 |
| kJ | 49 | 25 | 25 | 229 | 59 | 31 | 41 | 76 | 80 | 28 | 129 | 32 | 45 | 35 | 39 | 28 | 40 | 38 | 36 |
Wind waves Height (m) Direction Period (s) | ENE 10 | E 10 | E 9 | SSE 7 | ENE 8 | ENE 7 | ENE 7 | ENE 7 | ENE 6 | ENE 6 | E 9 | ENE 7 | ENE 7 | NE 6 | — | — | — | — | — |
| kJ | 2924 | 4262 | 1744 | 274 | 378 | 330 | 206 | 158 | 125 | 101 | 154 | 107 | 113 | 26 | — | — | — | — | — |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 46 | 330 | 133 | 126 | 38 | 38 | 16 | 31 | 31 | 16 | 31 | 31 | 16 | 31 | 31 | 12 | 14 | 33 | 12 |
Best forecast wave conditions in Kaua'i | |||||||||||||||||||
Best forecast wave conditions in United States | |||||||||||||||||||
Header Global | |||||||||||||||||||
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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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