Surf Forecasts:
Ammonias surf forecast from 18 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: Monday 24 Aug, 8PM (local time) - 7ft (2.2m), 8s period, ENE swell with 584 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. 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 Monday (Aug 24) at 8PM. Winds are predicted to be cross-shore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.9m 6s period and expected on Thursday (Aug 20) at 8AM.
| 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 | 8PM (Mon 24th Aug) | 7ft (2.2m) 8s |
Table - best surf conditions forecast for Ammonias over the next 16 days.
The Lowdown
Alright, Rusty here. I’m looking at the forecast for Ammonias, and it’s pretty grim over the next 16 days.
We’re staring down a long stretch of poor conditions. The wind is mostly cross-on or cross-shore from the east and northeast, blowing 12 to 15 mph, and it’s just messing up the water. The water temperature is about 80°F, which is normal for this time of year, so at least the water’s not cold.
The first tiny ray of hope is around Thursday, August 20th. The swell drops to about 2 feet from the SSW with a period of 18 seconds, that’s a long-period groundswell, but there’s hardly any energy in it (268). The wind will be light, maybe a little cross, so it might be clean, but it’s barely a wave. It’s described as "marginal."
We get a bump in size on Sunday, August 23rd, with swell from the ENE pushing 6 feet, but the period is a short 7 seconds, just windswell. The wind is still 15 mph and cross-shore, so it’s going to be a choppy, lumpy mess. The same story repeats for days – a bit of size, but bad wind and short period.
The closest we get to something half decent is around Wednesday, August 26th, and the following weekend. The swell builds from 7 to 8 feet, but it’s all short-period ENE windswell (6-8 seconds), and the wind is still 12-15 mph. The energy gets strong (up to 1357), but with those conditions, it’s just a big, sectiony, blown-out mess. For a reef break, that’s not good. It’s too big for beginners (over 5 feet) and close to expert-only (over 8 feet), but with this wind, it’s not even good for experts. The setup here is a reef, and with that short-period, onshore-driven swell, it’s going to be a washing machine. It might look more interesting for kite surfing than paddle surfing.
Heading into September, the swell fades back to under 3 feet, and the wind stays strong from the east. The best we can hope for is a tiny, clean day around the 20th of August, but it’s a long shot. This is a real blank run for Ammonias.
Rusty.
Short Range ForecastMostly dry. Warm (max 27°C on Thu afternoon, min 23°C on Tue night). Wind will be generally light. | Days 5-7 Weather SummaryMostly dry. Warm (max 27°C on Sat afternoon, min 24°C on Thu night). Wind will be generally light. | ||||||||||||||||||
Tuesday 18 | Wednesday 19 | Thursday 20 | Friday 21 | Saturday 22 | Sunday 23 | ||||||||||||||
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 7 | ENE 7 | ENE 6 | S 12 | ENE 6 | SW 16 | SSW 18 | SSW 17 | SW 16 | SSW 17 | SW 16 | SSW 16 | SW 16 | SSW 16 | E 7 | E 7 | ENE 7 | ENE 7 |
Wave Graph | |||||||||||||||||||
232 | 165 | 165 | 117 | 78 | 103 | 130 | 207 | 195 | 278 | 255 | 258 | 322 | 261 | 226 | 302 | 329 | 233 | 290 | |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross | cross-on | cross | cross | cross-on | cross | cross | cross | cross | cross-off | on | on | cross-off | cross-on | cross | cross | cross | cross | cross |
High Tide | 8:46AM0.48m | 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 | |||||||||
Low Tide | 00:55AM0.06m | 3:13PM0.30m | 1:28AM0.08m | 2:14AM0.09m | 3:21AM0.10m | 9:24PM0.19m | 9:13PM0.18m | 5:45AM0.08m | 9:16PM0.18m | ||||||||||
— | 6:16 | — | — | 6:16 | — | — | 6:16 | — | — | 6:16 | — | — | 6:16 | — | — | 6:16 | — | — | |
7:06 | — | 7:06 | — | — | 7:05 | — | — | 7:04 | — | — | 7:02 | — | — | 7:01 | — | — | 7:01 | — | |
mm | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
Temp °C | 25 | 25 | 25 | 24 | 25 | 26 | 24 | 26 | 27 | 25 | 26 | 26 | 26 | 26 | 27 | 25 | 26 | 26 | 25 |
Feels °C | 26 | 25 | 25 | 24 | 25 | 26 | 24 | 27 | 28 | 27 | 29 | 28 | 30 | 27 | 28 | 26 | 26 | 26 | 25 |
Swell 1 Height (m) Direction Period (s) | S 14 | S 13 | S 13 | S 13 | NNE 7 | SSE 9 | SW 16 | SSW 18 | E 8 | ENE 7 | ENE 7 | ENE 7 | SSW 16 | SW 16 | SSW 16 | SSW 16 | SSW 15 | SSW 15 | SSW 14 |
232 | 165 | 165 | 112 | 31 | 33 | 130 | 207 | 57 | 111 | 90 | 86 | 322 | 261 | 217 | 212 | 196 | 188 | 183 | |
Swell 2 Height (m) Direction Period (s) | SSE 6 | SE 10 | SE 10 | SSE 10 | SSE 9 | S 12 | SSE 9 | E 8 | SSW 17 | SW 16 | SSW 17 | SW 16 | W 10 | S 14 | WNW 11 | S 14 | S 13 | SE 10 | SE 14 |
14 | 45 | 47 | 63 | 59 | 69 | 33 | 31 | 195 | 278 | 255 | 258 | 50 | 153 | 100 | 107 | 92 | 60 | 121 | |
Swell 3 Height (m) Direction Period (s) | SE 11 | SW 17 | SW 18 | WNW 12 | S 12 | SSW 16 | S 12 | SSE 10 | SE 10 | SE 9 | W 10 | W 10 | SSE 14 | W 10 | SE 8 | WNW 11 | NW 11 | SSE 13 | SSE 13 |
41 | 76 | 80 | 28 | 69 | 103 | 44 | 36 | 23 | 21 | 52 | 51 | 62 | 54 | 18 | 44 | 29 | 35 | 56 | |
Wind waves Height (m) Direction Period (s) | ENE 7 | ENE 7 | ENE 7 | ENE 6 | E 6 | ENE 6 | ENE 7 | NE 6 | NE 6 | — | — | — | ENE 7 | ENE 6 | ENE 6 | E 7 | E 7 | ENE 7 | ENE 7 |
225 | 158 | 137 | 117 | 78 | 93 | 99 | 59 | 34 | — | — | — | 99 | 133 | 226 | 302 | 329 | 233 | 290 | |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 16 | 31 | 31 | 16 | 31 | 31 | 16 | 15 | 10 | 0 | 16 | 32 | 0 | 31 | 31 | 16 | 31 | 31 | 16 |
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











