Surf Forecasts:
Ammonias surf forecast from 15 Aug 2026:
- Best quality surf: Friday 21 Aug, 5AM (local time) - 2.5ft (0.8m), 17s period, SSW swell with cross-offshore winds.
- Most powerful swell: Sunday 16 Aug, 5AM (local time) - 15ft (4.5m), 10s period, E swell with 3,814 kJ wave energy.
- Next surfable swell (1★+): Friday 21 Aug, 5AM (local time) - 2.5ft (0.8m), 17s 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 Friday (Aug 21) at 5AM. The primary swell is predicted to be 0.8m and 17s 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 4.5m 10s and forecast to arrive on Sunday (Aug 16) at 5AM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.1m 8s period and expected on Saturday (Aug 22) at 5AM.
| Wave Type | Time (HST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 5AM (Fri 21st Aug) | 2.5ft (0.8m) 17s |
| Best Surf | 5AM (Fri 21st Aug) | 2.5ft (0.8m) 17s |
| Most Powerful | 5AM (Sun 16th Aug) | 15ft (4.5m) 10s |
Table - best surf conditions forecast for Ammonias over the next 16 days.
The Lowdown
Alright crew, Rusty here. Let’s break down what’s on the menu for Ammonias.
We’re in for a rough start. The first week is a write-off. Saturday the 15th has some serious swell, 8ft of ENE groundswell, but a 30 km/h cross-shore wind is gonna shred it into a lumpy, cross-chop nightmare. The wave energy is strong (1250 to 1734), but you can’t surf it if it’s a mess. The water temp is 80°F, right about normal for the time of year. It’s a reef break, so it needs a clean wind to work. Sunday the 16th is worse: 13ft of swell with a 45 km/h cross-onshore. That’s a big, ugly, dangerous day for experts only, and the wind is so bad it’s not even worth the paddle.
Through the 23rd, the wind just doesn’t let up. We get a few pulses of long-period SSW groundswell (16-18 seconds), but the energy is only moderate (357 to 474) and the wind is always cross or cross-onshore. The forecasts are calling it marginal, and that’s the truth. There’s no session in here that I’d get excited about. The first real chance comes way down the line.
The 27th of August is the day to circle. A long-period E swell with 18 seconds and solid energy (1879 to 2000) rolls in, and the wind finally drops to a moderate cross-shore, which makes a world of difference. The swell is 4ft, a nice size, and with that 18-second period, it’s a proper groundswell. This reef break is exposed and should start to pump out some clean lines. Finally, something worth paddling for. The 28th and 29th look similar, same swell direction and period, so that’s your best bet. The crowds are listed as "often," so it’s not a secret, but it’s worth it for the quality.
The standout window is the 27th to the 29th of August. The 30th could be a bit of a wild card too, with a 8ft E swell and more energy (1964), but the wind is a touch more onshore, so it might be a bit choppier. That’s a bigger wave, so it’s for the experienced crew.
It’s a long haul with a lot of flat or blown-out days in between, but there’s a light at the end of the tunnel. Keep your eyes on late August.
Rusty.
Short Range ForecastHeavy rain (total 50mm), heaviest during Sun morning. Warm (max 26°C on Sat morning, min 24°C on Sun morning). Winds decreasing (strong winds from the ENE on Sat night, light winds from the ESE by Sun night). | Days 4-6 Weather SummaryMostly dry. Warm (max 26°C on Tue morning, min 24°C on Tue night). Wind will be generally light. | ||||||||||||||||||||
Saturday 15 | Sunday 16 | Monday 17 | Tuesday 18 | Wednesday 19 | Thursday 20 | Friday 21 | |||||||||||||||
AM | 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 8 | ENE 9 | E 10 | ESE 10 | ENE 9 | ENE 8 | ENE 8 | ENE 7 | S 14 | S 13 | ENE 6 | ENE 6 | ENE 7 | ENE 7 | ENE 7 | SSW 18 | SSW 17 | SW 16 | SSW 17 | SW 16 | SSW 16 |
Wave Graph  | |||||||||||||||||||||
 kJ | 866 | 1469 | 3168 | 2956 | 898 | 561 | 408 | 294 | 232 | 168 | 144 | 104 | 137 | 129 | 149 | 207 | 195 | 278 | 255 | 258 | 322 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross | cross | cross | cross-on | cross-on | cross-on | cross-on | cross-on | cross | cross-on | cross-on | cross-on | cross-on | cross | cross | cross | cross | cross | cross | cross-on | cross |
High Tide | 5:29PM0.52m | 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 | 11:06AM0.12m | 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 | — | — | 6:15 | — | — | 6:16 | — | — | 6:16 | — | — | 6:16 | — | — | 6:16 | — | — |
 | — | 7:07 | — | — | 7:07 | — | — | 7:06 | — | — | 7:06 | — | — | 7:05 | — | — | 7:04 | — | — | 7:02 | — |
mm | — | 2 | 5 | 26 | 7 | 6 | 3 | 1 | — | — | — | — | — | — | — | — | — | — | — | — | — |
Temp °C | 26 | 26 | 25 | 25 | 26 | 26 | 26 | 26 | 25 | 26 | 26 | 25 | 26 | 26 | 25 | 26 | 26 | 25 | 26 | 26 | 25 |
Feels °C | 26 | 25 | 23 | 22 | 25 | 26 | 27 | 27 | 26 | 26 | 26 | 25 | 27 | 27 | 25 | 27 | 27 | 26 | 28 | 28 | 28 |
Swell 1 Height (m) Direction Period (s) | S 13 | S 13 | S 13 | S 13 | SE 8 | SSE 8 | S 14 | SSE 6 | S 14 | S 13 | S 13 | SSE 8 | S 12 | SE 9 | SW 16 | SSW 18 | SSW 17 | NE 7 | ENE 7 | ENE 8 | ENE 8 |
| kJ | 280 | 219 | 170 | 156 | 450 | 277 | 334 | 53 | 232 | 168 | 121 | 47 | 44 | 41 | 130 | 207 | 195 | 55 | 142 | 154 | 154 |
Swell 2 Height (m) Direction Period (s) | E 12 | S 16 | S 18 | S 17 | S 13 | S 14 | SE 7 | S 13 | SSE 6 | SSE 9 | SSE 10 | S 13 | SSW 16 | S 12 | SSE 9 | SE 9 | SE 9 | SW 16 | SSW 17 | SW 16 | SSW 16 |
| kJ | 104 | 46 | 98 | 143 | 157 | 179 | 73 | 153 | 13 | 59 | 64 | 79 | 103 | 69 | 33 | 21 | 22 | 278 | 255 | 258 | 322 |
Swell 3 Height (m) Direction Period (s) | W 13 | W 13 | WNW 12 | W 12 | S 16 | S 16 | S 7 | S 15 | SE 11 | SW 17 | SW 18 | WNW 12 | SE 6 | SSW 16 | S 12 | SW 8 | S 11 | E 8 | SE 9 | SE 9 | SE 9 |
| kJ | 29 | 30 | 29 | 25 | 183 | 127 | 43 | 150 | 29 | 76 | 80 | 28 | 10 | 103 | 44 | 17 | 23 | 54 | 40 | 38 | 37 |
Wind waves Height (m) Direction Period (s) | ENE 8 | ENE 9 | E 10 | ESE 10 | ENE 9 | ENE 8 | ENE 8 | ENE 7 | ENE 7 | ENE 6 | ENE 6 | ENE 6 | ENE 7 | ENE 7 | ENE 7 | ENE 7 | ENE 7 | — | — | — | — |
| kJ | 866 | 1469 | 3168 | 2956 | 898 | 561 | 408 | 294 | 219 | 144 | 144 | 104 | 137 | 129 | 149 | 136 | 117 | — | — | — | — |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 31 | 31 | 38 | 406 | 133 | 126 | 126 | 126 | 16 | 31 | 31 | 31 | 31 | 31 | 16 | 31 | 16 | 10 | 12 | 14 | 11 |
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
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