Ammonias Surf Break

Lat Long: 21.95° N 159.35° W

Ammonias Surf Forecast and Surf Report

Issued: 1 pm 20 Aug 2026 (local time)

Forecast update in  hr  min

Today's Ammonias sea temperature is
26.4° C
0.4° 

Ammonias surf forecast is for near shore open water. Breaking waves will often be smaller at less exposed spots.


Ammonias surf forecast from 21 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: Thursday 27 Aug, 2PM (local time) - 3.5ft (1.1m), 17s period, S swell with 686 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 1.2m 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 1.1m 17s and forecast to arrive on Thursday (Aug 27) at 2PM. 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 TypeTime (HST) & Date Wave Height & Period
Next good surf (1 star+)11PM (Thu 20th Aug)2.5ft (0.7m) 16s
Best Surf11PM (Thu 20th Aug)2.5ft (0.7m) 16s
Most Powerful 2PM (Thu 27th Aug)3.5ft (1.1m) 17s

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 cookin’ over the next couple weeks.

Honestly, the whole 16-day window is a bit of a struggle. We’re not talking shut-downs every day, but the quality just isn’t there to get excited about for most of it. We’ve got a long gap of marginal to poor conditions stretching from now right through to the end of August. The first real glimmer of something interesting doesn’t show up until the very end of the run, and even that comes with a but. Let’s break it down.

For the first ten days or so, from Thursday the 20th right through to the end of August, it’s mostly onshore or cross-shore breezes messing up the surface. Thursday the 20th has tiny 2 ft swell at 17 seconds, long period but weak combined energy of only 226 – pretty underwhelming, and with a cross breeze, it’s not doing much. Friday and the weekend stay small at 2 ft, with poor conditions flagged right through. By Sunday the 23rd, the swell bumps up to 6 ft but it’s short period windswell at 7 seconds from the east, and the wind is a fresh 19 mph cross-shore – lumpy and uninviting. That trend of messy, mid-range east swell with cross wind holds through Monday, Tuesday, and Wednesday. The combined energy climbs into the high hundreds and low thousands by late week, but the wind keeps everything choppy.

Now, the standout window – and it’s a big qualifier – appears right at the end. On Monday the 31st of August into Tuesday the 1st of September, we see a proper jump. Monday afternoon brings 8 ft swell from the ENE with a period stretching to 12 seconds, and the combined energy rockets to 2029 – that’s strong wave energy. The wind holds cross-shore at 16 mph, so it’s not glassy, but it’s rideable. By Tuesday morning, the swell peaks at 12 ft from the ENE with 11-second period and combined energy hitting 2856. The wind drops right back to a light 6 mph cross-on breeze – that’s promising for clean-ish conditions if it holds. This is serious size. 12 ft is advanced only – that’s expert territory. The offshore direction is a light cross-on, so it’s not perfect offshore, but with the wind that light, the surface will be workable.

Ammonias is the only break on offer, and at the end of the run, it looks like the best bet. On Monday the 31st and Tuesday the 1st, we’ve got that big ENE groundswell. With the period over 12 seconds, it’s a proper groundswell, and that works well for a reef setup like this. The optimum swell is from the SSE, so the ENE direction is a bit off, but the sheer size and energy make up for it. Water temperature is sitting around 80°F, which is about average for this time of year – nothing weird going on there. Be aware, this spot can get crowded, and it’s fairly consistent, so there will be others on it. For the few days leading up to that, from the 27th to the 30th, you’re looking at 3 ft to 4 ft southerly and easterly swell with cross winds – just not worth paddling out unless you’re desperate.

After Tuesday the 1st, the swell drops back to the 7-8 ft range on Wednesday the 2nd with a light onshore breeze, and then it tapers off through the 3rd and 4th back into the messy 6 ft east swell with cross wind. That second week loses the magic.

So, one standout: the end of the month into early September at Ammonias. Big, powerful ENE groundswell, light wind on Tuesday, expert-only size. That’s where I’d point the van.

Rusty.

Short Range Forecast

Mostly dry. Warm (max 27°C on Thu afternoon, min 25°C on Thu night). Wind will be generally light.

Days 5-7 Weather Summary

Light rain (total 2mm), mostly falling on Tue morning. Warm (max 27°C on Sun afternoon, min 24°C on Tue night). Wind will be generally light.

Thu
20
Friday
21
Saturday
22
Sunday
23
Monday
24
Tuesday
25
Wednesday
26
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
AM
PM
Night
Rating
(10 max)
1
1
0
0
1
0
0
0
0
0
0
0
0
1
0
1
1
1
1
1
Swell
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Height Map
Wave
Height (m)
Direction
Period (s)
0.6
SSW
17
0.7
SW
16
0.7
SSW
17
0.7
SW
16
0.8
SSW
16
0.7
SW
16
0.7
SW
16
1.7
E
7
1.9
E
7
1.9
ENE
7
1.7
E
7
0.7
SSW
14
1.6
ENE
6
1.6
ENE
6
1.7
E
7
1.7
E
7
1.6
ENE
7
0.7
SSW
14
0.8
S
18
0.9
S
19
Wave Graph
Metric surfscale
Energy kJ
195
278
255
258
322
261
251
270
361
352
255
212
218
200
255
286
238
215
399
555
Wind (km/h)
15
ENE
10
NE
10
SE
10
SE
15
ENE
20
ENE
25
ENE
25
ENE
30
ENE
25
NE
25
ENE
25
ENE
25
ENE
20
ENE
20
ENE
20
ENE
20
ENE
25
ENE
20
NE
20
NE
Wind State
cross
cross
on
on
cross
cross-on
cross
cross
cross
cross
cross
cross
cross
cross
cross-on
cross
cross
cross
cross
cross
High Tide
12:20PM0.56m
11:30PM0.20m
1:07PM0.59m
00:35AM0.22m
1:46PM0.62m
1:16AM0.25m
2:19PM0.63m
1:51AM0.28m
2:48PM0.64m
2:25AM0.31m
3:14PM0.64m
3:02AM0.35m
Low Tide
3:21AM0.10m
9:24PM0.19m
9:13PM0.18m
5:45AM0.08m
9:16PM0.18m
6:37AM0.05m
9:23PM0.17m
7:21AM0.04m
9:34PM0.16m
8:01AM0.03m
9:50PM0.13m
clear
clear
clear
clear
clear
clear
clear
part cloud
clear
clear
clear
clear
clear
part cloud
rain showers
thunderstorm
part cloud
part cloud
clear
part cloud
<span class="translation_missing" title="translation missing: en.weather_tables.sunrise">Sunrise</span>
6:16
6:16
6:16
6:16
6:18
6:18
<span class="translation_missing" title="translation missing: en.weather_tables.sunset">Sunset</span>
7:04
7:02
7:01
7:01
7:00
7:00
6:59
 mm
1
1
Temp °C
27
26
27
27
26
26
27
25
26
27
25
26
26
25
26
26
25
25
26
25
Feels °C
30
29
30
29
30
27
28
26
25
27
25
25
26
25
27
26
26
23
25
25
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  • Live Wave Height (m)
  • Live Wind Speed (km/h)
  • Surf Rating (10 Max)
  • Ocean Swells (m)
  • Wind Speed (km/h)
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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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