Surf Forecasts:
Mainside surf forecast from 26 Aug 2026:
- Best quality surf: Saturday 29 Aug, 12AM (local time) - 1.5ft (0.5m), 10s period, W swell with offshore winds.
- Most powerful swell: Wednesday 2 Sep, 3PM (local time) - 18ft (5.5m), 10s period, NNW swell with 5,360 kJ wave energy.
- Next surfable swell (1★+): Saturday 29 Aug, 12AM (local time) - 1.5ft (0.5m), 10s 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 Saturday (Aug 29) at 12AM. The primary swell is predicted to be 0.5m and 10s period with a secondary swell of 0.5m and 8s. The wind is predicted to be offshore as the swell arrives.
The most powerful waves expected at Mainside in the next 16 days are 5.5m 10s and forecast to arrive on Wednesday (Sep 02) at 3PM. Winds are predicted to be onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 2.5m 14s period and expected on Wednesday (Sep 02) at 6AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 12AM (Sat 29th Aug) | 1.5ft (0.5m) 10s |
| Best Surf | 12AM (Sat 29th Aug) | 1.5ft (0.5m) 10s |
| Most Powerful | 3PM (Wed 2nd Sep) | 18ft (5.5m) 10s |
Table - best surf conditions forecast for Mainside over the next 16 days.
The Lowdown
Alright, Rusty here. Let’s talk Mainside in feet and Fahrenheit for those who think that way.
Water temp is a warm 83°, right where you’d expect it for this time of year in the tropics. No weird anomalies.
The start is rubbish. Wednesday the 26th is a near gale, 60 km/h cross-shore wind, smashing an 8ft mess. Don’t bother. Thursday the 27th is still marginal – 8ft to 7ft of average junk under a moderate breeze. You are waiting until Friday the 28th morning for anything clean. Finally, a SE offshore wind at 30 km/h cleans up a 4ft WNW swell. Energy is low (313), so it’s small and weak. Saturday the 29th drops to 2ft and then flat-ish.
We hit a dead zone from Sunday the 30th through Tuesday the 1st of September. Strong onshores and storm threats. A 6ft windswell on the 1st is short-period and all chopped up.
Wednesday the 2nd of September goes ballistic. An 18ft swell from the NNW, energy of (5959). But the wind is onshore at 30 km/h, making it a total washing machine. Dangerous, ugly, huge.
Thursday the 3rd is a 16ft NW groundswell with a long 12-second period, and the wind is a light cross-onshore. Energy is massive (7695). At that size, only experts need apply. The reef at Mainside will handle it, but you better know what you’re doing.
The absolute standout is Friday the 4th of September afternoon. The swell drops to 8ft from the NW, and the wind goes glassy. That’s a dream window for experienced surfers. Clean, powerful, and lined up.
Saturday the 5th is a nice 5ft with a clean offshore breeze. Smaller, but fun.
Sunday the 6th drops off. Monday the 7th morning, glassy again with a 10ft NNW swell – another expert window, but the wind shifts onshore later.
From the 8th to the 10th, it’s all cross-shore and lumpy. Nothing special.
Best bet: Friday the 4th of September afternoon. Glassy, 8ft, NW groundswell. That’s the one to circle.
Rusty.
Short Range ForecastModerate rain (total 11mm), heaviest on Wed morning. Warm (max 29°C on Wed afternoon, min 28°C on Wed morning). Winds decreasing (near gales from the SW on Wed morning, moderate winds from the S by Thu morning). | Days 4-6 Weather SummaryLight rain (total 8mm), mostly falling on Mon night. Warm (max 29°C on Sat morning, min 27°C on Sat night). Winds increasing (light winds from the ENE on Sat night, strong winds from the NNE by Mon afternoon). | ||||||||||||||||||||
Wednesday 26 | Thursday 27 | Friday 28 | Saturday 29 | Sunday 30 | Monday 31 | Tuesday 1 | |||||||||||||||
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) | NW 9 | WNW 9 | W 10 | W 10 | W 10 | WNW 10 | WNW 10 | W 9 | W 10 | W 8 | E 13 | ENE 12 | SE 9 | ENE 12 | ESE 10 | SE 10 | SE 10 | SE 10 | NNE 6 | NNE 7 | N 8 |
Wave Graph  | |||||||||||||||||||||
 kJ | 1202 | 1107 | 1584 | 963 | 896 | 754 | 288 | 133 | 45 | 34 | 30 | 30 | 0 | 14 | 0 | 0 | 0 | 0 | 200 | 385 | 814 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross | cross | cross | cross-off | cross-off | cross-off | off | off | off | off | off | cross-off | cross-off | cross-off | cross-off | cross | cross | cross | cross-on | on | on |
High Tide | 7:07PM1.92m | 6:28AM1.97m | 7:28PM2.00m | 7:03AM2.08m | 7:50PM2.07m | 7:38AM2.16m | 8:14PM2.11m | 8:14AM2.20m | 8:39PM2.14m | 8:52AM2.18m | 9:06PM2.15m | 9:32AM2.11m | 9:36PM2.12m | ||||||||
Low Tide | 12:33PM0.45m | 00:51AM0.99m | 1:03PM0.38m | 1:16AM0.84m | 1:32PM0.34m | 1:43AM0.70m | 2:01PM0.34m | 2:13AM0.58m | 2:31PM0.39m | 2:45AM0.47m | 3:01PM0.49m | 3:20AM0.42m | 3:33PM0.63m | ||||||||
 | |  |  | |  |  | | | | | | | | | | | | | | | |
 | 6:05 | — | — | 6:05 | — | — | 6:05 | — | — | 6:07 | — | — | 6:07 | — | — | 6:07 | — | — | 6:07 | — | — |
 | — | 6:55 | — | — | 6:54 | — | — | 6:53 | — | — | 6:52 | — | — | 6:52 | — | — | 6:51 | — | — | 6:49 | — |
mm | 7 | 2 | 1 | — | 1 | — | — | — | — | — | — | — | — | — | — | 1 | 2 | 5 | 4 | 3 | 3 |
Temp °C | 28 | 29 | 28 | 29 | 29 | 28 | 29 | 29 | 28 | 29 | 29 | 27 | 29 | 29 | 27 | 28 | 28 | 27 | 28 | 28 | 28 |
Feels °C | 23 | 27 | 27 | 29 | 30 | 31 | 30 | 30 | 29 | 30 | 30 | 29 | 29 | 29 | 26 | 27 | 27 | 26 | 28 | 29 | 28 |
Swell 1 Height (m) Direction Period (s) | NW 9 | WNW 9 | W 10 | W 10 | W 10 | WNW 10 | WNW 10 | W 9 | SW 9 | SW 9 | SSW 9 | SSW 9 | SE 9 | SE 9 | ESE 10 | SE 10 | SE 10 | SE 10 | SE 12 | SE 13 | ESE 13 |
| kJ | 1202 | 1107 | 1584 | 963 | 896 | 754 | 288 | 133 | 123 | 120 | 101 | 103 | 91 | 135 | 264 | 204 | 245 | 292 | 361 | 424 | 1668 |
Swell 2 Height (m) Direction Period (s) | E 10 | E 9 | ESE 8 | ESE 8 | SW 8 | E 12 | SW 9 | SW 9 | W 8 | W 8 | W 8 | ENE 12 | SW 8 | SW 9 | SSW 9 | SW 10 | SW 10 | SW 10 | ESE 10 | E 10 | SW 10 |
| kJ | 74 | 26 | 22 | 19 | 72 | 11 | 112 | 95 | 31 | 34 | 10 | 30 | 58 | 81 | 25 | 33 | 37 | 25 | 154 | 184 | 15 |
Swell 3 Height (m) Direction Period (s) | E 15 | E 14 | E 13 | E 13 | E 7 | E 16 | E 12 | S 8 | W 10 | ENE 13 | E 13 | W 7 | S 9 | ENE 12 | SW 9 | SSW 10 | SSW 9 | SSW 9 | SW 10 | SE 18 | SW 10 |
| kJ | 4 | 16 | 31 | 30 | 17 | 5 | 25 | 10 | 45 | 17 | 30 | 4 | 16 | 14 | 29 | 18 | 16 | 8 | 16 | 114 | 15 |
Wind waves Height (m) Direction Period (s) | WSW 8 | SSW 7 | S 6 | SSW 9 | S 4 | SSE 8 | SE 6 | SE 6 | SE 6 | ESE 7 | SE 7 | ESE 7 | E 4 | E 4 | — | ENE 4 | NE 4 | NNE 5 | NNE 6 | NNE 7 | N 8 |
| kJ | 906 | 383 | 160 | 132 | 16 | 149 | 113 | 98 | 91 | 76 | 63 | 84 | 6 | 6 | — | 28 | 27 | 87 | 200 | 385 | 814 |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 608 | 600 | 600 | 618 | 600 | 6 | 14 | 14 | 0 | 0 | 14 | 10 | 10 | 10 | 608 | 650 | 608 | 608 | 830 | 36 | 36 |
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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