Surf Forecasts:
Mainside surf forecast from 21 Aug 2026:
- Best quality surf: Friday 28 Aug, 6PM (local time) - 3.5ft (1.1m), 9s period, W swell with offshore winds.
- Most powerful swell: Tuesday 25 Aug, 12PM (local time) - 10ft (3.0m), 17s period, E swell with 5,536 kJ wave energy.
- Next surfable swell (1★+): Friday 28 Aug, 6PM (local time) - 3.5ft (1.1m), 9s period with W swell.
Best Forecast Surf Conditions for Mainside this week:
The surf forecast for Mainside over the next 16 days: The first swell (rated 1 star or higher) is forecast to arrive on Friday (Aug 28) at 6PM. The primary swell is predicted to be 1.1m and 9s period. The wind is predicted to be offshore as the swell arrives.
The most powerful waves expected at Mainside in the next 16 days are 3.0m 17s and forecast to arrive on Tuesday (Aug 25) at 12PM. Winds are predicted to be cross-shore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 3.0m 18s period and expected on Tuesday (Aug 25) at 6AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 6PM (Fri 28th Aug) | 3.5ft (1.1m) 9s |
| Best Surf | 6PM (Fri 28th Aug) | 3.5ft (1.1m) 9s |
| Most Powerful | 12PM (Tue 25th Aug) | 10ft (3.0m) 17s |
Table - best surf conditions forecast for Mainside over the next 16 days.
The Lowdown
Alright, Rusty here. Let’s have a look at what Mainside has in store for us.
The outlook for the next 16 days starts with a real bummer. We’ve got a stretch of almost no surf and poor conditions right through the weekend and into Monday the 26th of August. The first few days are a write-off – strong cross-off winds and tiny, weak swell. It’s not worth paddling out for that.
Now, Tuesday the 27th of August is where things get interesting. We see a big, powerful east-northeast groundswell rolling in, about 10ft with a very long 17-second period from the east. The energy is absolutely pumping (combined swell energy 4695), which is serious stuff. This is a big, powerful swell – definitely for advanced surfers only at that size. The wind is onshore and sideshore though, so it won't be clean perfection, but the power is undeniable.
That swell continues into Wednesday the 28th of August, still a solid 8ft from the north, with shorter period. The wind turns onshore here too, making conditions marginal.
We get a glimmer of hope on Friday the 30th of August. The wave comment says "expect very good surf conditions" which is a standout signal. Swell drops to a manageable 6ft from the northwest, with a 10-second period. The key here is the wind – light southeast breeze, cross-off, which should keep the wave face clean. The energy is still decent at 789. This is a solid option for a surfer who can handle head-high-plus surf.
After Friday, the swell drops off quickly. Saturday the 31st of August and Sunday the 1st of September offer tiny, weak swell with poor conditions, and then we're into a long, frustrating stretch through the first week of September. From the 2nd of September onwards, we are looking at persistent strong cross-shore winds and a lot of lumpy, messy conditions. There is some size on Thursday the 5th – a solid 8ft to 10ft from the north – but the fresh north-northeast breeze will chop it up badly. It’s not recommended for a paddle surf.
This Mainside reef is consistent overall, but with the wind patterns, it’s mostly going to be a frustrating run for the paddle surfer. The Friday the 30th of August window is the one to circle on your calendar as the standout – for clean conditions at a decent size. The big groundswell on the 27th and 28th is for the experienced crew only, and even then, it won't be perfect.
Rusty.
Short Range ForecastLight rain (total 5mm), mostly falling on Sat morning. Warm (max 29°C on Sun afternoon, min 27°C on Sat night). Mainly strong winds. | Days 4-6 Weather SummaryModerate rain (total 10mm), heaviest on Wed night. Warm (max 29°C on Tue morning, min 28°C on Tue morning). Mainly strong winds. | ||||||||||||||||||||
Saturday 22 | Sunday 23 | Monday 24 | Tuesday 25 | Wednesday 26 | Thursday 27 | Friday 28 | |||||||||||||||
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 9 | ENE 9 | ENE 9 | E 14 | E 9 | E 10 | ESE 15 | E 13 | ENE 7 | E 17 | E 16 | NNW 8 | N 11 | WNW 11 | WNW 11 | W 11 | W 11 | W 11 | W 11 | W 10 | W 10 |
Wave Graph  | |||||||||||||||||||||
 kJ | 8 | 8 | 16 | 37 | 6 | 7 | 0 | 3 | 93 | 5428 | 4889 | 1405 | 2403 | 3342 | 2696 | 2513 | 1898 | 1242 | 646 | 320 | 143 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-off | cross-off | off | off | off | off | off | off | cross-off | cross | cross | cross-on | on | on | cross-on | cross-on | cross-on | cross-off | cross-off | cross-off | off |
High Tide | 5:17PM1.48m | 2:15AM1.61m | 6:02PM1.61m | 4:01AM1.63m | 6:26PM1.73m | 5:05AM1.73m | 6:47PM1.83m | 5:50AM1.85m | 7:07PM1.92m | 6:28AM1.97m | 7:28PM2.00m | 7:03AM2.08m | 7:50PM2.07m | ||||||||
Low Tide | 8:41PM1.43m | 10:25AM0.77m | 11:03PM1.37m | 11:21AM0.66m | 11:53PM1.25m | 12:00PM0.54m | 00:24AM1.12m | 12:33PM0.45m | 00:51AM0.99m | 1:03PM0.38m | 1:16AM0.84m | 1:32PM0.34m | 1:43AM0.70m | ||||||||
 |  |  | | |  | | |  | | | |  | |  | | | | | | | |
 | 6:03 | — | — | 6:03 | — | — | 6:03 | — | — | 6:05 | — | — | 6:05 | — | — | 6:05 | — | — | 6:05 | — | — |
 | — | 7:00 | — | — | 6:59 | — | — | 6:58 | — | — | 6:57 | — | — | 6:55 | — | — | 6:54 | — | — | 6:53 | — |
mm | 1 | — | 2 | — | — | — | 1 | 1 | — | — | 1 | 1 | — | — | 3 | 1 | 2 | 2 | 1 | — | — |
Temp °C | 28 | 28 | 27 | 28 | 29 | 28 | 28 | 28 | 27 | 29 | 29 | 29 | 28 | 28 | 28 | 28 | 28 | 28 | 29 | 29 | 28 |
Feels °C | 27 | 28 | 28 | 29 | 30 | 30 | 30 | 29 | 28 | 31 | 30 | 30 | 29 | 29 | 29 | 27 | 27 | 27 | 30 | 31 | 31 |
Swell 1 Height (m) Direction Period (s) | SSW 8 | SE 10 | SSW 10 | SW 10 | SW 10 | SW 9 | SW 9 | ESE 16 | ESE 18 | E 17 | E 16 | NNE 10 | N 11 | WNW 11 | WNW 11 | W 11 | W 11 | W 11 | W 11 | W 10 | SSW 9 |
| kJ | 241 | 23 | 516 | 400 | 269 | 162 | 118 | 761 | 3056 | 5428 | 4889 | 679 | 2403 | 3342 | 2696 | 2513 | 1898 | 1242 | 646 | 320 | 165 |
Swell 2 Height (m) Direction Period (s) | ENE 9 | ENE 9 | ESE 10 | E 14 | ESE 13 | ESE 12 | ESE 15 | SSW 9 | SSW 9 | SW 9 | SSW 9 | ENE 14 | E 11 | ESE 10 | E 9 | ESE 9 | E 8 | ESE 9 | E 8 | SSW 8 | W 10 |
| kJ | 8 | 8 | 18 | 37 | 18 | 30 | 146 | 101 | 88 | 36 | 55 | 1049 | 57 | 33 | 23 | 58 | 48 | 137 | 50 | 160 | 143 |
Swell 3 Height (m) Direction Period (s) | — | — | ENE 9 | SE 10 | E 9 | E 10 | SE 9 | E 13 | ENE 10 | — | — | SSW 9 | SE 10 | E 14 | E 13 | S 8 | SSE 8 | SSW 9 | E 12 | ESE 8 | E 8 |
| kJ | — | — | 16 | 4 | 6 | 7 | 3 | 3 | 19 | — | — | 100 | 17 | 15 | 14 | 36 | 46 | 54 | 11 | 35 | 29 |
Wind waves Height (m) Direction Period (s) | S 9 | SSW 10 | SSE 6 | ESE 4 | ESE 4 | ESE 4 | E 4 | E 4 | ENE 7 | NNE 5 | N 6 | NNW 8 | W 9 | S 11 | SSW 5 | — | SW 9 | SSW 9 | SSW 9 | ESE 8 | ESE 7 |
| kJ | 904 | 978 | 85 | 14 | 16 | 16 | 12 | 18 | 93 | 80 | 267 | 1405 | 1359 | 37 | 109 | — | 115 | 144 | 202 | 79 | 73 |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 600 | 650 | 14 | 14 | 14 | 14 | 14 | 14 | 10 | 39 | 39 | 36 | 15 | 36 | 24 | 608 | 608 | 608 | 618 | 6 | 0 |
Best forecast wave conditions in Okinawa | |||||||||||||||||||||
Best forecast wave conditions in Japan | |||||||||||||||||||||
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Information about the Mainside Surf forecast
The above surf forecast table for Mainside provides essential information for determining whether the surfing conditions will be good over the next 16 days. A general guide to surfing at Mainside can be found by selecting the local surf guide option on the grey menu. Our Mainside 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 (Mainside) 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 Mainside 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.
Mainside is 11 km (7 miles) from the city of Ishikawa. If you plan a holiday in Okinawa, look for hotels and other accommodation in Ishikawa. Ishikawa has rooms for a wide range of budgets as well as car hire and transport links.
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