Surf Forecasts:
Mainside surf forecast from 31 Aug 2026:
- Best quality surf: Thursday 3 Sep, 3AM (local time) - 4.5ft (1.3m), 10s period, E swell with offshore winds.
- Most powerful swell: Tuesday 1 Sep, 3PM (local time) - 6ft (1.9m), 9s period, E swell with 601 kJ wave energy.
- Next surfable swell (1★+): Thursday 3 Sep, 3AM (local time) - 4.5ft (1.3m), 10s period with E 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 Thursday (Sep 03) at 3AM. The primary swell is predicted to be 1.3m and 10s 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 1.9m 9s and forecast to arrive on Tuesday (Sep 01) at 3PM. Winds are predicted to be offshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 2.0m 9s period and expected on Tuesday (Sep 01) at 6PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 3AM (Thu 3rd Sep) | 4.5ft (1.3m) 10s |
| Best Surf | 3AM (Thu 3rd Sep) | 4.5ft (1.3m) 10s |
| Most Powerful | 3PM (Tue 1st Sep) | 6ft (1.9m) 9s |
Table - best surf conditions forecast for Mainside over the next 16 days.
The Lowdown
Alright, let’s talk Mainside. The next two weeks are pretty quiet overall. The swell is small and inconsistent for most of it, with a few clean windows. Water temp is about 83°F at the start, which is normal for this time of year.
We start flat. Monday morning through Tuesday afternoon, nothing is happening. Small waves, windy, not worth a paddle.
Then Wednesday afternoon the 2nd of September, we get a pulse of 5ft swell from the east with a 9-second period. Combined energy is moderate (401). Offshore wind from the ESE at 19 mph, so it’ll be clean. The period is short, so it won’t have much grunt, and there’s a risk of thunderstorms.
The real highlight is Thursday morning the 3rd of September. A 4ft swell from the east, 10-second period, combined energy of 261 (moderate), and super light offshore winds from the ESE at 6 mph. That’s glassy and clean. The reef will shape it up nicely. It’s an advanced break, so not for beginners. Expect crowds sometimes.
Saturday the 5th of September afternoon has a 4ft north swell, 10-second period, combined energy 284 (moderate), and gentle offshore winds from the SE at 9 mph. Clean, but not a standout.
After that, it fades. Sunday the 6th and onward are small. Monday the 7th afternoon has a 6ft east swell, but the period is only 6 seconds, and it’s windy – messy. The rest of the second week is weak, with cross-shore winds and tiny surf. The last few days from the 13th to the 15th of September are almost flat, with poor conditions.
The best bet is Thursday morning the 3rd of September at Mainside. Clean, light offshore, and that 4ft east swell will be the best you’ll see.
Rusty.
Short Range ForecastHeavy rain (total 29mm), heaviest during Tue night. Warm (max 29°C on Mon afternoon, min 27°C on Mon morning). Mainly fresh winds. | Days 4-6 Weather SummaryLight rain (total 5mm), mostly falling on Thu night. Warm (max 30°C on Fri morning, min 27°C on Thu morning). Wind will be generally light. | ||||||||||||||||||||
Monday 31 | Tuesday 1 | Wednesday 2 | Thursday 3 | Friday 4 | Saturday 5 | Sunday 6 | |||||||||||||||
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 11 | ENE 11 | E 8 | E 15 | E 9 | E 9 | E 9 | E 9 | E 10 | E 10 | E 10 | E 9 | N 7 | N 7 | N 6 | N 9 | N 10 | N 9 | N 8 | N 8 | N 9 |
Wave Graph  | |||||||||||||||||||||
 kJ | 12 | 12 | 0 | 4 | 601 | 588 | 455 | 390 | 392 | 237 | 123 | 60 | 39 | 35 | 31 | 122 | 268 | 207 | 82 | 57 | 56 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | off | cross-off | cross-off | off | off | off | off | off | off | off | cross | cross-off | cross-off | cross-off | cross-off | off | off | off | off | off | cross |
High Tide | 9:06PM2.15m | 9:32AM2.11m | 9:36PM2.12m | 10:17AM1.97m | 10:08PM2.07m | 11:11AM1.79m | 10:46PM1.98m | 12:27PM1.61m | 11:36PM1.86m | 2:36PM1.53m | 1:00AM1.75m | 4:38PM1.63m | |||||||||
Low Tide | 3:01PM0.49m | 3:20AM0.42m | 3:33PM0.63m | 4:00AM0.41m | 4:07PM0.80m | 4:48AM0.46m | 4:45PM1.00m | 5:47AM0.54m | 5:33PM1.19m | 7:11AM0.62m | 7:06PM1.35m | 8:59AM0.62m | 9:37PM1.34m | ||||||||
 | |  |  | | | | | |  | | | | |  | | |  | | | | |
 | 6:07 | — | — | 6:07 | — | — | 6:07 | — | — | 6:09 | — | — | 6:09 | — | — | 6:09 | — | — | 6:09 | — | — |
 | — | 6:51 | — | — | 6:49 | — | — | 6:47 | — | — | 6:46 | — | — | 6:45 | — | — | 6:45 | — | — | 6:44 | — |
mm | — | — | 1 | 4 | 4 | 7 | 6 | 4 | 3 | — | — | 2 | — | — | — | 1 | 1 | 1 | — | — | — |
Temp °C | 28 | 29 | 27 | 28 | 28 | 27 | 27 | 28 | 27 | 28 | 29 | 28 | 30 | 30 | 28 | 29 | 29 | 28 | 29 | 29 | 27 |
Feels °C | 29 | 30 | 28 | 28 | 28 | 27 | 27 | 28 | 28 | 32 | 32 | 31 | 33 | 33 | 32 | 32 | 32 | 32 | 33 | 33 | 30 |
Swell 1 Height (m) Direction Period (s) | S 9 | S 9 | SW 9 | SW 10 | SW 9 | SW 10 | SW 10 | SW 10 | SW 10 | SW 10 | SW 11 | SW 12 | SW 10 | SSW 10 | S 10 | SSW 9 | N 10 | N 9 | SSW 9 | SSE 9 | SSW 8 |
| kJ | 41 | 39 | 26 | 33 | 41 | 120 | 239 | 304 | 377 | 341 | 413 | 594 | 255 | 150 | 188 | 213 | 268 | 207 | 168 | 134 | 96 |
Swell 2 Height (m) Direction Period (s) | SW 9 | SW 10 | SSW 8 | SSW 8 | S 8 | E 14 | E 16 | E 12 | E 10 | E 10 | E 10 | E 9 | S 11 | SW 10 | SW 9 | N 9 | SSW 8 | S 8 | N 8 | SW 8 | N 9 |
| kJ | 40 | 33 | 24 | 13 | 5 | 15 | 5 | 11 | 392 | 237 | 123 | 60 | 112 | 100 | 83 | 122 | 160 | 173 | 82 | 98 | 56 |
Swell 3 Height (m) Direction Period (s) | ENE 11 | ENE 11 | S 8 | E 15 | E 15 | S 7 | — | — | — | NNE 6 | S 9 | N 7 | N 7 | N 7 | N 6 | ESE 7 | E 10 | E 9 | E 9 | N 8 | E 12 |
| kJ | 12 | 12 | 10 | 4 | 5 | 4 | — | — | — | 20 | 61 | 24 | 39 | 35 | 31 | 11 | 16 | 27 | 15 | 57 | 10 |
Wind waves Height (m) Direction Period (s) | ESE 7 | ESE 9 | E 8 | ESE 9 | E 9 | E 9 | E 9 | E 9 | NNE 5 | SW 3 | — | — | — | — | — | — | — | — | SE 4 | — | ESE 4 |
| kJ | 91 | 232 | 324 | 484 | 601 | 588 | 455 | 390 | 11 | 4 | — | — | — | — | — | — | — | — | 27 | — | 43 |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 14 | 11 | 650 | 621 | 608 | 600 | 600 | 600 | 1 | 0 | 15 | 1 | 25 | 14 | 10 | 0 | 0 | 0 | 0 | 0 | 10 |
Best forecast wave conditions in Okinawa | |||||||||||||||||||||
Best forecast wave conditions in Japan | |||||||||||||||||||||
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The surf report / weather widget below is available to embed on third party websites free of charge and provides a summary of our Mainside surf forecast. Simply grab the html code snippet that we provide and paste it into your own site. You can choose your preferred language and metric/imperial units for the surf forecast feed to suit users of your site. Click here to get the code.
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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