Surf Forecasts:
Ammonias surf forecast from 19 Aug 2026:
- Best quality surf: Thursday 20 Aug, 11PM (local time) - 2.5ft (0.7m), 16s period, SSW swell with cross-offshore winds.
- Most powerful swell: Tuesday 25 Aug, 8AM (local time) - 7ft (2.2m), 8s period, ENE swell with 555 kJ wave energy.
- Next surfable swell (1★+): Thursday 20 Aug, 11PM (local time) - 2.5ft (0.7m), 16s period with SSW 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 Thursday (Aug 20) at 11PM. The primary swell is predicted to be 0.7m and 16s period with a secondary swell of 0.9m and 7s. 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 2.2m 8s and forecast to arrive on Tuesday (Aug 25) at 8AM. Winds are predicted to be cross-shore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.1m 7s period and expected on Friday (Aug 21) at 5AM.
| Wave Type | Time (HST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 11PM (Thu 20th Aug) | 2.5ft (0.7m) 16s |
| Best Surf | 11PM (Thu 20th Aug) | 2.5ft (0.7m) 16s |
| Most Powerful | 8AM (Tue 25th Aug) | 7ft (2.2m) 8s |
Table - best surf conditions forecast for Ammonias over the next 16 days.
The Lowdown
Alright, Rusty here. Let's have a look at what's cooking for this stretch.
Right off the bat, for the next couple of weeks, it’s a tough gig. The forecast is a real mixed bag of cross-shore winds and choppy conditions that just won't let the waves line up properly. The water temperature is sitting at 80°, which is pretty much what you'd expect for this time of year, nothing unusual there.
We start on Tuesday the 18th with a small, 0.7 ft south swell, but it's got that cross-shore wind messing it up. The energy's moderate (437), but with a "poor surf conditions" tag, you're better off cleaning your board.
Wednesday the 19th through to Thursday the 20th stays pretty grim. The swell drops to 0.4 ft to 0.6 ft, driven by long-period SSW groundswell (16-18 seconds). That long period would normally get you excited, but with a constant cross-shore breeze from the ENE, it's just a bumpy mess.
Now, there's a tiny window that's worth mentioning. Friday the 21st. We get a bit of a reprieve. The wind goes light, even turning onshore but very light, from the ESE then SE. The swell sits at 0.7 ft from the SSW, with a period of 16-17 seconds (combined energy around 255-316). It’s only a "marginal" call, but with a light breeze, that could be the cleanest, most ridable little waves we see all week.
After that, things go downhill again. From Saturday the 22nd right through the end of the month, the wind cranks back up to 20-25 km/h from the ENE. The swell builds, but it's all short-period wind chop (7-8 seconds) from the east and east-northeast. The energy climbs from moderate to strong (from 469 up to over 1000), but the quality is just not there. The wave comment is nearly always "poor surf conditions". By the 25th and 26th of August, we're looking at 7 ft to 8 ft of chunky, short-period swell with risk of thunderstorms. That's a lot of water moving around, but it's going to be blown-out and ugly. It's more of a kite-surfing session than a proper paddle-surf.
We get a brief uptick in energy on the 29th of August, with the combined energy hitting 1111, but it's still cross-shore winds and a 9-second period. Then the swell backs off again into early September.
But hold on. If you're patient, there’s a light at the end of the tunnel. The standout here, the one to circle on your calendar, is Wednesday the 2nd of September. A new groundswell arrives from the south. The swell height is a modest 1 ft, but the period is a massive 20 seconds. That’s a proper, powerful line of swell. The wind is down to a gentle 15 km/h breeze from the NE, keeping the surface cross but not too choppy. The combined energy is through the roof at 1799 and 1818. This is a setup that screams quality. With that long period, it will wrap into the reef at Ammonias with a lot of push and length.
For a reef break, this is the one. The long period makes it less ideal for a beach break, but for a reef setup, it's textbook. It’s a bit far out in the forecast, so treat it as a promising look, but a damn good one.
Overall, the next two weeks are a write-off for quality waves. The only game in town is a very early, light-wind window on Friday the 21st for knee-high waves, and then the big, clean groundswell prospect on the 2nd of September.
Rusty.
Short Range ForecastMostly dry. Warm (max 27°C on Fri morning, min 24°C on Tue night). Wind will be generally light. | Days 5-7 Weather SummarySome drizzle, heaviest during Sun night. Warm (max 27°C on Fri afternoon, min 25°C on Fri night). Wind will be generally light. | |||||||||||||||||||
Tue 18 | Wednesday 19 | Thursday 20 | Friday 21 | Saturday 22 | Sunday 23 | Monday 24 | ||||||||||||||
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) | ENE 7 | S 13 | SW 16 | ENE 6 | ENE 7 | SSW 18 | SSW 17 | SW 16 | SSW 17 | SW 16 | SSW 16 | SW 16 | SW 16 | ENE 7 | E 7 | E 7 | ENE 7 | ENE 7 | ENE 7 | E 8 |
Wave Graph | ||||||||||||||||||||
165 | 112 | 129 | 103 | 130 | 207 | 195 | 278 | 255 | 258 | 322 | 261 | 251 | 261 | 331 | 311 | 316 | 268 | 308 | 504 | |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross | cross | cross | cross | cross-on | cross | cross-on | cross-off | on | on | cross-on | cross-on | cross | cross | cross | cross | cross | cross | cross | cross |
High Tide | 5:31PM0.30m | 10:06AM0.50m | 11:20AM0.53m | 12:20PM0.56m | 11:30PM0.20m | 1:07PM0.59m | 00:35AM0.22m | 1:46PM0.62m | 1:16AM0.25m | 2:19PM0.63m | 1:51AM0.28m | |||||||||
Low Tide | 3:13PM0.30m | 1:28AM0.08m | 2:14AM0.09m | 3:21AM0.10m | 9:24PM0.19m | 9:13PM0.18m | 5:45AM0.08m | 9:16PM0.18m | 6:37AM0.05m | 9:23PM0.17m | ||||||||||
— | — | 6:16 | — | — | 6:16 | — | — | 6:16 | — | — | 6:16 | — | — | 6:16 | — | — | 6:16 | — | — | |
7:06 | — | — | 7:05 | — | — | 7:04 | — | — | 7:02 | — | — | 7:01 | — | — | 7:01 | — | — | 7:00 | — | |
mm | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 1 | — | — | 2 |
Temp °C | 26 | 25 | 25 | 26 | 24 | 26 | 26 | 25 | 27 | 27 | 26 | 27 | 27 | 25 | 26 | 27 | 25 | 26 | 26 | 25 |
Feels °C | 26 | 26 | 25 | 27 | 25 | 27 | 27 | 28 | 30 | 29 | 29 | 28 | 27 | 26 | 26 | 27 | 25 | 26 | 26 | 25 |
Swell 1 Height (m) Direction Period (s) | S 13 | S 13 | SSE 9 | SSE 9 | SW 16 | E 8 | E 8 | NE 7 | NE 7 | SW 16 | SSW 16 | SW 16 | SW 16 | SSW 16 | SSW 15 | SE 12 | SSW 14 | SE 12 | SE 12 | SE 10 |
165 | 112 | 59 | 33 | 130 | 61 | 41 | 84 | 119 | 258 | 322 | 261 | 251 | 212 | 196 | 132 | 183 | 148 | 146 | 98 | |
Swell 2 Height (m) Direction Period (s) | SE 10 | SSE 10 | S 12 | S 12 | S 12 | SSW 18 | SSW 17 | SW 16 | SSW 17 | NE 7 | W 10 | WNW 11 | W 11 | WNW 11 | S 13 | SSW 15 | SE 12 | SSW 14 | SSW 13 | SSW 12 |
47 | 63 | 69 | 69 | 44 | 207 | 195 | 278 | 255 | 47 | 51 | 93 | 57 | 69 | 92 | 188 | 89 | 166 | 156 | 89 | |
Swell 3 Height (m) Direction Period (s) | SW 18 | E 9 | SW 16 | SSW 16 | SSE 9 | SSE 10 | SSE 10 | E 8 | W 10 | ENE 8 | SSE 14 | S 15 | SE 8 | S 14 | WNW 11 | SSE 13 | SSE 13 | NW 12 | SSW 18 | SSW 16 |
80 | 24 | 129 | 103 | 32 | 36 | 35 | 32 | 53 | 58 | 62 | 109 | 17 | 107 | 46 | 59 | 57 | 34 | 61 | 105 | |
Wind waves Height (m) Direction Period (s) | ENE 7 | ENE 6 | ENE 7 | ENE 6 | ENE 7 | NE 6 | NE 7 | — | — | — | ENE 7 | ENE 7 | ENE 6 | ENE 7 | E 7 | E 7 | ENE 7 | ENE 7 | ENE 7 | E 8 |
145 | 103 | 105 | 96 | 117 | 40 | 52 | — | — | — | 132 | 158 | 201 | 261 | 331 | 311 | 316 | 268 | 308 | 504 | |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 16 | 16 | 31 | 31 | 31 | 31 | 12 | 0 | 31 | 10 | 16 | 31 | 16 | 16 | 16 | 33 | 16 | 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











