Surf Forecasts:
Ammonias surf forecast from 13 Aug 2026:
- Most powerful swell: Sunday 16 Aug, 8PM (local time) - 10ft (3.0m), 11s period, SSE swell with 2,171 kJ wave energy.
Best Forecast Surf Conditions for Ammonias this week:
The most powerful waves expected at Ammonias in the next 16 days are 3.0m 11s and forecast to arrive on Sunday (Aug 16) at 8PM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.3m 12s period and expected on Thursday (Aug 13) at 8AM.
| Wave Type | Time (HST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | - | - |
| Best Surf | - | - |
| Most Powerful | 8PM (Sun 16th Aug) | 10ft (3.0m) 11s |
Table - best surf conditions forecast for Ammonias over the next 16 days.
The Lowdown
Alright folks, Rusty here. Let’s have a look at what’s on the cards for Ammonias.
Right off the bat, I gotta be straight with you – the next 16 days are not looking like a classic. It’s a long stretch of messy, cross-shore winds and lumpy conditions that are gonna make things tough. There’s a bit of swell energy around, but it’s being blown out by a persistent breeze from the ENE and NE. The early part of the period is a write-off for a decent paddle.
We do see a bit of a pulse of south swell arriving on Wednesday, August 12th. The wave energy is strong, hitting 1165 (moderate energy), with a 4 ft swell from the south at a very long 18 seconds. That’s proper groundswell. But here’s the kicker – the wind is a cross-shore 16 mph, and the forecast says it’s marginal. It’s not going to be clean, but for a reef break at Ammonias, that long period south swell might wrap in and give a few rideable ones, especially if you’re patient. The water temp is 80°, which is bang on average for this time of year.
Things go downhill fast from there. Thursday, August 13th through Friday, August 14th stay cross-shore and messy, with the swell dropping in period. By Saturday, August 15th, the swell direction swings to the ENE and the period drops to a short 8 seconds, while the height jumps up to 8 ft. That’s a lot of chunky, wind-affected water. The combined energy jumps to 1257 (moderate), but with rain showers and a fresh 19 mph cross-shore, it’s a messy onshore mess. Sunday, August 16th is the worst of it – 12 ft of short-period ENE windswell and a strong 25 mph cross-shore breeze. That’s not paddle surfing; that’s a kite session or a hard pass. The wave energy hits 3313 (very strong), but it’s unsurfable.
After that, from Monday, August 17th right through to the end of August, we’re looking at a long stretch of poor-to-marginal conditions. The swell drops off, the period stays short (7-8 seconds), and the wind remains a cross or cross-on shore. The wave energy drops to weak levels by the 19th, dipping below 300 (low energy). There’s a little flicker of life around the 23rd-25th of August, with a south swell trying to build again, reaching 4 ft and a period of 16 seconds by the 25th. The energy hits 881 (moderate), but the wind is still cross-shore.
Honestly, if you’re desperate for a wave, the best bet is to keep an eye on the morning of Wednesday, August 12th, or maybe the very end of the window around the 25th-27th of August. But even then, it’s marginal. The crowds at Ammonias can be an issue, and with the northeast wind, it’s rarely going to be glassy. The setup is a reef, so the long period south swells might make it a bit better than the beach, but it’s a gamble.
For now, I’d say the only standout, if you can call it that, is the south swell on the 12th of August. The rest is a waiting game.
Rusty.
Short Range ForecastLight rain (total 3mm), mostly falling on Fri night. Warm (max 27°C on Wed afternoon, min 25°C on Wed night). Mainly fresh winds. | Days 5-7 Weather SummaryHeavy rain (total 21mm), heaviest during Sun night. Warm (max 26°C on Sat afternoon, min 24°C on Mon night). Mainly fresh winds. | |||||||||||||||||||
Wed 12 | Thursday 13 | Friday 14 | Saturday 15 | Sunday 16 | Monday 17 | Tuesday 18 | ||||||||||||||
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 18 | S 16 | S 16 | S 15 | S 15 | S 14 | S 14 | ENE 8 | ENE 8 | ENE 9 | E 9 | ENE 9 | ENE 9 | ENE 8 | ENE 8 | ENE 7 | S 14 | ENE 7 | ENE 7 | ENE 7 |
Wave Graph | ||||||||||||||||||||
741 | 1178 | 1004 | 784 | 743 | 598 | 496 | 526 | 956 | 1245 | 1703 | 1592 | 1652 | 1001 | 555 | 426 | 254 | 178 | 158 | 141 | |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross | cross-on | cross | cross | cross | cross | cross | cross | cross | cross | cross | cross | cross | cross-on | cross-on | cross | cross-on | cross-on | cross | cross |
High Tide | 4:02PM0.71m | 3:54AM0.34m | 4:34PM0.66m | 4:44AM0.37m | 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 | |||||||
Low Tide | 10:44PM0.10m | 9:30AM-0.00m | 11:09PM0.08m | 10:17AM0.05m | 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 | |||||||
— | — | 6:13 | — | — | 6:13 | — | — | 6:15 | — | — | 6:15 | — | — | 6:15 | — | — | 6:16 | — | — | |
7:09 | — | — | 7:08 | — | — | 7:08 | — | — | 7:07 | — | — | 7:07 | — | — | 7:06 | — | — | 7:06 | — | |
mm | — | — | — | — | — | — | — | 1 | 2 | 2 | 4 | 2 | 2 | 10 | 1 | — | — | — | — | — |
Temp °C | 27 | 25 | 27 | 27 | 25 | 26 | 27 | 25 | 26 | 26 | 25 | 25 | 25 | 25 | 25 | 26 | 25 | 26 | 26 | 25 |
Feels °C | 26 | 24 | 26 | 25 | 25 | 24 | 26 | 24 | 26 | 25 | 24 | 23 | 22 | 23 | 24 | 25 | 24 | 26 | 26 | 26 |
Swell 1 Height (m) Direction Period (s) | S 18 | S 16 | S 16 | S 15 | S 15 | S 14 | S 14 | S 14 | S 13 | S 13 | S 13 | SE 12 | SE 11 | SSE 8 | SSE 7 | SSE 7 | S 14 | S 13 | S 13 | SSE 9 |
741 | 1178 | 1004 | 784 | 743 | 598 | 496 | 394 | 280 | 219 | 219 | 457 | 1310 | 443 | 101 | 59 | 232 | 165 | 121 | 68 | |
Swell 2 Height (m) Direction Period (s) | SSW 13 | SE 9 | W 12 | SE 9 | W 12 | SE 12 | SE 12 | SE 13 | W 13 | S 16 | SE 14 | S 12 | S 13 | S 13 | S 14 | S 12 | SSE 6 | SSE 8 | SSE 9 | S 13 |
289 | 22 | 25 | 14 | 10 | 21 | 21 | 26 | 29 | 46 | 73 | 150 | 168 | 168 | 338 | 150 | 44 | 39 | 50 | 78 | |
Swell 3 Height (m) Direction Period (s) | SE 9 | W 12 | SW 19 | W 11 | SE 12 | W 12 | W 11 | W 11 | SE 12 | W 13 | S 18 | S 17 | S 16 | S 16 | SE 11 | S 15 | SE 11 | SW 17 | SW 18 | WNW 12 |
20 | 25 | 14 | 23 | 6 | 11 | 22 | 21 | 21 | 30 | 98 | 142 | 183 | 181 | 19 | 150 | 18 | 76 | 80 | 28 | |
Wind waves Height (m) Direction Period (s) | ENE 6 | ENE 6 | ENE 6 | ENE 6 | ENE 7 | ENE 7 | ENE 8 | ENE 8 | ENE 8 | ENE 9 | E 9 | ENE 9 | ENE 9 | ENE 8 | ENE 8 | ENE 7 | ENE 7 | ENE 7 | ENE 7 | ENE 7 |
115 | 160 | 170 | 183 | 360 | 403 | 406 | 526 | 956 | 1245 | 1703 | 1592 | 1652 | 1001 | 555 | 426 | 254 | 178 | 158 | 141 | |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 16 | 33 | 16 | 31 | 15 | 31 | 31 | 31 | 31 | 31 | 31 | 31 | 38 | 126 | 126 | 38 | 38 | 31 | 31 | 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











