
Surf Forecasts:
Ammonias surf forecast from 12 Aug 2026:
- Most powerful swell: Monday 17 Aug, 5AM (local time) - 13ft (4.0m), 11s period, ENE swell with 3,882 kJ wave energy.
Best Forecast Surf Conditions for Ammonias this week:
The most powerful waves expected at Ammonias in the next 16 days are 4.0m 11s and forecast to arrive on Monday (Aug 17) at 5AM. Winds are predicted to be 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 | 5AM (Mon 17th Aug) | 13ft (4.0m) 11s |
Table - best surf conditions forecast for Ammonias over the next 16 days.
The Lowdown
Alright, surfers, ol’ Rusty here with the long-range look. Gotta be straight with you – this one’s a tough read for Ammonias. This is a reef setup that really needs the stars to align, and for the most part, they’re just not lining up.
We’ve got a gap right at the start with absolutely no surf on offer through the early part of the window. The first real chance to even think about a paddle comes Wednesday afternoon, the 12th of August, but even then it’s only a marginal 4ft of swell coming from the S with a solid 18-second period. That’s a proper groundswell, with a combined wave energy of 1186 (moderate). The trouble? Wind's cross-shore from the NE at 16 mph, putting a chop on it. It's gonna be a lumpy, tricky one to line up, and honestly, for a reef break, you want that wind either light or offshore. The crowd factor is there too – this spot can get busy, so you’ll be fighting for position in less-than-ideal conditions.
Thursday morning, the 13th, bumps up a touch to 5ft from the S, 16-second period. Wave energy is similar at 1188 (moderate), but the cross-shore wind sticks around. It’s still only a marginal call.
Then we hit a proper rough patch. From Thursday afternoon all the way through to the 24th of August, it's a long stretch of poor surf quality. The swell sticks around but the winds turn ugly, especially around the 15th and 16th where we see 7ft to 8ft of windswell from the ENE with period down around 8 seconds. Combined energy jumps up to 1790 (strong), but with near-gale force cross-onshore winds at 34 mph on the Sunday, it’ll be a total mess. That’s blown-out, choppy chaos, more for the kite crew than anyone on a paddle board.
There’s a bit of a tease toward the end of the window, particularly on Monday morning the 24th of August. We get some long-period S/SSW groundswell around 3ft, but with a 17 to 18-second period. Wave energy is moderate at 1259. The wind is still cross-shore though, so it’s only marginal. For a reef break like Ammonias, that long-period energy can be magic if the wind cleans up, but here it’s just a "could've been" scenario.
The water is sitting at a pretty normal 80° for this time of year, so no surprises there.
Look, the standout moment – and I use that term loosely – is probably the Wednesday morning, the 12th, or Thursday morning, the 13th, if you’re desperate for a paddle. The swell has some proper S groundswell energy, and the period is decent. But the wind is a constant thorn in our side. For a clean session here, we’d need that ENE wind to drop or swing offshore from the NW. As it stands, it’s a long wait for very little reward. Keep an eye on it, but don’t hold your breath.
Rusty.
Short Range ForecastSome drizzle, heaviest during Wed night. Warm (max 27°C on Tue afternoon, min 24°C on Tue night). Wind will be generally light. | Days 5-7 Weather SummaryHeavy rain (total 46mm), 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 Mon morning). | |||||||||||||||||||
Tue 11 | Wednesday 12 | Thursday 13 | Friday 14 | Saturday 15 | Sunday 16 | Monday 17 | ||||||||||||||
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) | SSW 14 | S 20 | S 18 | S 18 | S 16 | S 16 | S 15 | S 15 | S 14 | S 14 | S 14 | ENE 8 | ENE 8 | ENE 9 | ENE 10 | ENE 10 | ENE 10 | ENE 10 | ENE 9 | E 8 |
Wave Graph | ||||||||||||||||||||
269 | 373 | 515 | 741 | 1178 | 1004 | 784 | 743 | 598 | 496 | 394 | 549 | 694 | 1282 | 1393 | 1153 | 3472 | 1340 | 727 | 558 | |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | cross | cross-on | cross | cross-on | cross | cross | cross | cross | cross | cross | cross | cross | cross | cross-on | cross-on | cross-on | cross-on | cross-on | cross-on |
High Tide | 3:26PM0.74m | 3:06AM0.30m | 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 | |||||||
Low Tide | 10:20PM0.12m | 8:43AM-0.04m | 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 | |||||||
— | — | 6:13 | — | — | 6:13 | — | — | 6:13 | — | — | 6:15 | — | — | 6:15 | — | — | 6:15 | — | — | |
7:10 | — | — | 7:09 | — | — | 7:08 | — | — | 7:08 | — | — | 7:07 | — | — | 7:07 | — | — | 7:06 | — | |
mm | — | — | — | — | 1 | — | — | — | — | — | — | 2 | 2 | 5 | 23 | 6 | 8 | — | 2 | 2 |
Temp °C | 27 | 25 | 26 | 26 | 25 | 27 | 27 | 25 | 26 | 27 | 25 | 27 | 26 | 26 | 26 | 26 | 26 | 27 | 27 | 25 |
Feels °C | 27 | 26 | 26 | 26 | 24 | 26 | 26 | 25 | 25 | 26 | 24 | 26 | 25 | 25 | 21 | 24 | 25 | 29 | 29 | 26 |
Swell 1 Height (m) Direction Period (s) | SSW 14 | SSW 13 | SSW 13 | S 18 | S 16 | S 16 | S 15 | S 15 | S 14 | S 14 | S 14 | S 13 | S 13 | S 13 | S 12 | S 13 | S 13 | ENE 10 | ENE 9 | S 14 |
269 | 299 | 289 | 741 | 1178 | 1004 | 784 | 743 | 598 | 496 | 394 | 345 | 276 | 215 | 193 | 157 | 167 | 1340 | 727 | 232 | |
Swell 2 Height (m) Direction Period (s) | SE 9 | S 20 | S 18 | SSW 13 | SE 9 | W 12 | SE 9 | W 12 | SE 12 | SE 12 | SE 13 | SE 11 | SE 12 | S 18 | S 17 | S 16 | S 16 | S 14 | SE 8 | SE 11 |
40 | 373 | 515 | 289 | 22 | 25 | 14 | 23 | 22 | 21 | 59 | 46 | 51 | 98 | 204 | 183 | 125 | 334 | 71 | 19 | |
Swell 3 Height (m) Direction Period (s) | SSW 11 | SE 9 | SE 9 | SE 9 | WNW 12 | SW 19 | W 11 | SE 9 | W 12 | W 11 | W 11 | W 13 | S 19 | WNW 12 | WNW 12 | WNW 11 | WNW 11 | SE 11 | S 12 | W 11 |
41 | 37 | 36 | 26 | 27 | 14 | 23 | 14 | 11 | 22 | 21 | 29 | 65 | 49 | 47 | 41 | 24 | 43 | 150 | 20 | |
Wind waves Height (m) Direction Period (s) | ENE 7 | ENE 7 | ENE 7 | ENE 6 | ENE 6 | ENE 6 | ENE 6 | ENE 6 | ENE 7 | ENE 7 | ENE 7 | ENE 8 | ENE 8 | ENE 9 | ENE 10 | ENE 10 | ENE 10 | — | SE 7 | E 8 |
132 | 147 | 131 | 130 | 150 | 170 | 170 | 252 | 328 | 294 | 376 | 549 | 694 | 1282 | 1393 | 1153 | 3472 | — | 107 | 558 | |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 31 | 16 | 31 | 31 | 16 | 16 | 33 | 16 | 31 | 31 | 31 | 31 | 31 | 31 | 406 | 133 | 118 | 125 | 126 | 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











