
Surf Forecasts:
Ammonias surf forecast from 15 Sep 2026:
- Most powerful swell: Tuesday 22 Sep, 8AM (local time) - 7ft (2.2m), 9s period, E swell with 725 kJ wave energy.
Best Forecast Surf Conditions for Ammonias this week:
The most powerful waves expected at Ammonias in the next 16 days are 2.2m 9s and forecast to arrive on Tuesday (Sep 22) 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 1.9m 7s period and expected on Thursday (Sep 17) at 11AM.
| Wave Type | Time (HST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | - | - |
| Best Surf | - | - |
| Most Powerful | 8AM (Tue 22nd Sep) | 7ft (2.2m) 9s |
Table - best surf conditions forecast for Ammonias over the next 16 days.
The Lowdown
Well folks, Rusty here. Let’s be straight with you: the next week and a half is looking pretty grim for any real surf action at Ammonias (Big Island). We’ve got some swell moving through, but it’s messy, short-period stuff, and the wind is just not playing ball. The water temp is sitting at 27°, which is right around normal for this time of year, so no drama there, just don’t expect any miracles.
For the next several days, we’re dealing with a solid cross-shore breeze and lumpy conditions. The swell is there, hovering around 0.7m to 1.0m, but the period is short, mostly in the 8 to 12 second range, and the energy is all over the place. The combined energy reads 490 on Tuesday morning, and it bumps up to 744 by Wednesday afternoon, but that’s not helping since the wind is chopping it all up. Honestly, Tuesday through to the following Monday is a write-off. The waves are weak, the period is too short, and that cross-shore wind is just making it bumpy. You’d be fighting it the whole time.
Now, hold on, because things start to get interesting around Wednesday, September 23rd. That’s when the light switches. The wind drops out, going light and clean, and the swell starts to pick up some proper punch. On the 23rd morning, we’re looking at 2.1m of east swell with a period around 10 seconds, and the energy jumps to 1114. The wind is a gentle cross-offshore breeze, and the surf conditions are rated excellent for experienced surfers. This is the one to keep an eye on.
But the real standout? That’s Thursday, September 24th. Morning and afternoon, that’s our best window. The wind goes glassy – I’m talking 5 km/h, clean, no ripples. The swell is holding strong at 2.0m to 2.3m from the ENE. That’s proper size, but it’s pushing the 2.5m mark, so this is one for the experienced crew, not the beginners. The period is a touch short at 8 to 9 seconds, but with that glassy surface and the energy at 1062 to 1146, it’s going to be hollow and fun on the reef. This is your standout day.
Friday morning, September 25th, is also worth getting up early for. Still 2.3m of ENE swell, but the wind turns a bit cross-offshore, keeping it clean. It’s still good, but that Thursday glass is the magic window.
After that, the swell starts to drop off and the wind gets funky again. By the 26th and 27th, we’re seeing the size back down and the wind turning more onshore. The period also drops back into the short range, which at a place like this means it’ll be softer and less defined. It’s not going to be terrible, but it won’t be that clean, powerful push we had mid-week.
One thing to note – those bigger swells, especially anything over 1.8m, are going to be pretty fat for the beachies. Keep in mind that longer period swells are best for points and reefs, and while we have a bit of that, the short period stuff is just going to close out. Stick to the reef and pick your moments. The message is clear: don’t waste your energy on the first week, but pencil in Thursday, September 24th as the day to clear your schedule. It’s not often we get glass and size together like that.
Alright, that’s the long and short of it. I’ll see you out there when it turns on.
Rusty.
Short Range ForecastModerate rain (total 12mm), heaviest on Thu night. Warm (max 27°C on Wed morning, min 24°C on Tue morning). Wind will be generally light. | Days 4-6 Weather SummaryModerate rain (total 10mm), heaviest on Fri morning. Warm (max 27°C on Sat morning, min 24°C on Sat night). Wind will be generally light. | ||||||||||||||||||||
Tuesday 15 | Wednesday 16 | Thursday 17 | Friday 18 | Saturday 19 | Sunday 20 | Monday 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) | SW 20 | SW 19 | SSW 19 | SW 18 | SSW 18 | SSW 17 | SW 16 | ENE 8 | SSW 18 | SSW 17 | SSW 16 | SSW 16 | E 8 | SSW 16 | ENE 8 | SSW 15 | ENE 8 | ENE 8 | ENE 8 | ENE 8 | E 8 |
Wave Graph | |||||||||||||||||||||
392 | 384 | 465 | 449 | 541 | 443 | 258 | 419 | 651 | 608 | 566 | 532 | 407 | 407 | 450 | 500 | 468 | 449 | 449 | 460 | 548 | |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross | cross | cross | cross | cross | cross-off | cross | cross | cross | cross | cross | cross | cross | cross | cross | cross | cross | cross | cross | cross | cross |
High Tide | 4:58PM0.30m | 7:44AM0.54m | 9:00AM0.53m | 10:23AM0.54m | 9:42PM0.19m | 11:33AM0.55m | 11:46PM0.22m | 12:24PM0.57m | 00:31AM0.26m | 1:03PM0.59m | 1:07AM0.30m | ||||||||||
Low Tide | 1:23PM0.26m | 11:40PM0.08m | 00:11AM0.10m | 00:58AM0.13m | 9:18PM0.19m | 8:14PM0.19m | 8:09PM0.18m | 5:23AM0.13m | 8:11PM0.17m | ||||||||||||
6:24 | — | — | 6:24 | — | — | 6:24 | — | — | 6:24 | — | — | 6:24 | — | — | 6:24 | — | — | 6:24 | — | — | |
— | 6:39 | — | — | 6:38 | — | — | 6:37 | — | — | 6:37 | — | — | 6:36 | — | — | 6:35 | — | — | 6:34 | — | |
mm | — | — | — | 1 | — | — | 2 | 2 | 7 | 4 | 2 | 2 | — | — | 1 | 1 | — | — | — | — | 4 |
Temp °C | 26 | 26 | 26 | 27 | 27 | 25 | 26 | 26 | 26 | 26 | 26 | 25 | 27 | 27 | 25 | 26 | 26 | 25 | 26 | 27 | 25 |
Feels °C | 27 | 27 | 29 | 28 | 28 | 25 | 26 | 26 | 27 | 26 | 25 | 25 | 27 | 27 | 25 | 25 | 25 | 25 | 26 | 27 | 26 |
Swell 1 Height (m) Direction Period (s) | SW 20 | SW 19 | SSW 19 | SW 18 | SSW 18 | SSW 17 | SW 16 | SSW 16 | SSW 18 | SSW 17 | SSW 16 | SSW 16 | SSW 15 | SSW 16 | S 16 | SSW 15 | SSW 15 | SSW 14 | S 14 | SSW 14 | SSW 13 |
392 | 384 | 465 | 449 | 541 | 443 | 258 | 326 | 651 | 608 | 566 | 532 | 367 | 382 | 257 | 500 | 468 | 449 | 405 | 304 | 232 | |
Swell 2 Height (m) Direction Period (s) | NNE 8 | SW 12 | E 11 | E 11 | E 10 | E 10 | E 10 | SSW 19 | SSE 10 | S 20 | SSE 9 | SSE 7 | SE 9 | S 18 | SSW 13 | N 11 | W 12 | W 12 | W 11 | W 11 | NNW 12 |
34 | 38 | 39 | 36 | 32 | 52 | 96 | 214 | 10 | 33 | 9 | 34 | 41 | 160 | 120 | 2 | 11 | 11 | 9 | 10 | 29 | |
Swell 3 Height (m) Direction Period (s) | SW 12 | E 12 | SW 12 | SW 11 | SW 11 | SW 11 | SSW 19 | SW 10 | WSW 9 | WSW 9 | S 21 | S 20 | S 18 | W 8 | SW 16 | W 13 | N 11 | N 11 | NNW 10 | N 10 | S 16 |
40 | 26 | 37 | 33 | 43 | 30 | 214 | 15 | 8 | 8 | 36 | 67 | 162 | 1 | 121 | 3 | 2 | 9 | 10 | 2 | 19 | |
Wind waves Height (m) Direction Period (s) | ENE 8 | NE 8 | NE 8 | NE 6 | ENE 6 | ENE 7 | NE 7 | ENE 8 | ENE 9 | ENE 8 | ENE 8 | ENE 8 | E 8 | E 8 | ENE 8 | E 7 | ENE 8 | ENE 8 | ENE 8 | ENE 8 | E 8 |
58 | 119 | 110 | 116 | 128 | 237 | 332 | 419 | 623 | 472 | 406 | 395 | 407 | 407 | 450 | 447 | 416 | 437 | 449 | 460 | 548 | |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 31 | 31 | 16 | 31 | 16 | 15 | 31 | 31 | 16 | 16 | 33 | 16 | 31 | 16 | 16 | 31 | 31 | 16 | 16 | 16 | 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










