Surf Forecasts:
Mainside surf forecast from 13 Sep 2026:
- Best quality surf: Monday 14 Sep, 9PM (local time) - 2.5ft (0.7m), 9s period, E swell with cross-offshore winds.
- Most powerful swell: Sunday 20 Sep, 9AM (local time) - 6ft (1.8m), 15s period, E swell with 1,511 kJ wave energy.
- Next surfable swell (1★+): Monday 14 Sep, 9PM (local time) - 2.5ft (0.7m), 9s 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 Monday (Sep 14) at 9PM. The primary swell is predicted to be 0.7m and 9s period with a secondary swell of 0.2m and 5s. The wind is predicted to be cross-offshore as the swell arrives.
The most powerful waves expected at Mainside in the next 16 days are 1.8m 15s and forecast to arrive on Sunday (Sep 20) at 9AM. Winds are predicted to be cross-shore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 0.7m 9s period and expected on Monday (Sep 14) at 9AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 9PM (Mon 14th Sep) | 2.5ft (0.7m) 9s |
| Best Surf | 9PM (Mon 14th Sep) | 2.5ft (0.7m) 9s |
| Most Powerful | 9AM (Sun 20th Sep) | 6ft (1.8m) 15s |
Table - best surf conditions forecast for Mainside over the next 16 days.
The Lowdown
Alright, this is Rusty. Let's talk about Mainside. It's a reef break that is consistent, exposed, and likes a northerly swell. The water is sitting at 84°, which is about normal for this time of year.
Right now, the outlook is pretty grim for a while. We've got a long gap of poor to average conditions through the middle of the month. The best of a bad bunch is on Wednesday the 16th morning, with a light 0.7m swell (2ft) out of the east and a cross-offshore breeze. The wave energy is moderate (150), but it's just a surfable wave in very ordinary conditions. You wouldn't paddle out for this, but you wouldn't be completely skunked if you had to.
Things start to look a bit more interesting around the 24th of September. On Thursday morning, we get a bit of a reprieve. The wind goes glassy, with a slight air out of the southwest. The swell is small, just 0.8m (3ft) from the north, but with no wind, it'll be clean. It's not going to be pumping, but it's a window of opportunity for a fun little session.
Then we get a real standout on the 29th of September, Tuesday morning. This is a big one. The swell is a massive 6.5m (21ft) from the north, with a long period of 11 seconds (a solid groundswell). The combined wave energy is over 10,000 – that’s very strong. But here’s the catch: it’s predicted to be too big for this break. This is for experts only, and even then, it's on the edge. The wind is a moderate cross-shore, so it won't be clean, but the raw power will be there. This is a promise for the brave, but it's over a week away, so keep an eye on it.
For the first week, don't get your hopes up. It’s a long, quiet stretch. The end of the month has the potential for a serious, heavy session for those who can handle it.
Rusty.
Short Range ForecastModerate rain (total 13mm), heaviest on Mon morning. Warm (max 28°C on Mon afternoon, min 26°C on Mon night). Wind will be generally light. | Days 4-6 Weather SummaryLight rain (total 6mm), mostly falling on Thu afternoon. Warm (max 28°C on Thu morning, min 26°C on Thu night). Winds increasing (light winds from the ENE on Thu morning, fresh winds from the N by Sat night). | ||||||||||||||||||||
Monday 14 | Tuesday 15 | Wednesday 16 | Thursday 17 | Friday 18 | Saturday 19 | Sunday 20 | |||||||||||||||
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) | E 13 | E 9 | E 9 | E 9 | E 10 | E 10 | E 10 | E 9 | NNW 7 | ENE 14 | E 9 | N 7 | N 7 | N 7 | N 9 | E 15 | E 16 | E 16 | E 15 | E 15 | E 14 |
Wave Graph  | |||||||||||||||||||||
 kJ | 31 | 76 | 78 | 81 | 88 | 89 | 90 | 62 | 61 | 38 | 41 | 34 | 35 | 34 | 15 | 376 | 1001 | 1438 | 1511 | 1373 | 985 |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | off | cross | cross-off | cross-off | cross | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross | cross | cross | cross | cross | cross | cross-on | cross-on |
High Tide | 8:54PM2.14m | 9:30AM1.97m | 9:19PM2.09m | 10:06AM1.82m | 9:44PM2.01m | 10:45AM1.67m | 10:10PM1.90m | 11:36AM1.52m | 10:38PM1.77m | 1:12PM1.41m | 11:17PM1.63m | 4:27PM1.47m | 1:01AM1.51m | ||||||||
Low Tide | 2:56PM0.61m | 3:19AM0.37m | 3:20PM0.75m | 3:52AM0.44m | 3:44PM0.89m | 4:28AM0.53m | 4:08PM1.03m | 5:09AM0.65m | 4:32PM1.18m | 6:06AM0.76m | 5:06PM1.32m | 7:38AM0.84m | 8:16PM1.42m | ||||||||
 | |  | | |  |  | | | | | | | |  | | | | | | | |
 | 6:13 | — | — | 6:13 | — | — | 6:13 | — | — | 6:15 | — | — | 6:15 | — | — | 6:15 | — | — | 6:16 | — | — |
 | — | 6:35 | — | — | 6:34 | — | — | 6:32 | — | — | 6:31 | — | — | 6:30 | — | — | 6:30 | — | — | 6:28 | — |
mm | 2 | 1 | 2 | 2 | 1 | 3 | — | 1 | 1 | — | 3 | 1 | 1 | 1 | — | — | — | — | — | — | — |
Temp °C | 27 | 28 | 27 | 28 | 28 | 27 | 28 | 28 | 27 | 28 | 28 | 27 | 27 | 27 | 27 | 27 | 28 | 27 | 27 | 27 | 27 |
Feels °C | 29 | 30 | 29 | 31 | 31 | 30 | 32 | 31 | 30 | 32 | 31 | 30 | 30 | 28 | 28 | 28 | 29 | 27 | 26 | 25 | 25 |
Swell 1 Height (m) Direction Period (s) | ESE 9 | E 9 | E 9 | E 9 | E 10 | E 10 | E 10 | NNW 7 | NNW 7 | NNW 6 | E 9 | N 7 | N 7 | E 9 | ESE 9 | E 15 | E 16 | E 16 | E 15 | E 15 | E 14 |
| kJ | 77 | 76 | 78 | 81 | 88 | 89 | 90 | 47 | 54 | 32 | 41 | 33 | 35 | 23 | 25 | 376 | 1001 | 1438 | 1511 | 1373 | 985 |
Swell 2 Height (m) Direction Period (s) | N 5 | N 5 | NNW 5 | NNW 6 | N 6 | NNW 6 | NNW 6 | E 9 | E 9 | E 9 | N 6 | E 9 | E 9 | ENE 12 | ESE 17 | ESE 8 | S 8 | S 8 | S 8 | S 8 | S 8 |
| kJ | 8 | 4 | 10 | 12 | 16 | 18 | 20 | 62 | 61 | 42 | 20 | 24 | 25 | 14 | 54 | 24 | 5 | 5 | 5 | 5 | 5 |
Swell 3 Height (m) Direction Period (s) | E 13 | E 13 | E 13 | E 13 | E 12 | SW 8 | ENE 14 | ENE 14 | ENE 14 | ENE 14 | N 6 | ENE 13 | ENE 12 | S 8 | N 9 | S 8 | — | — | — | — | — |
| kJ | 31 | 14 | 31 | 28 | 12 | 2 | 40 | 37 | 40 | 38 | 7 | 34 | 30 | 5 | 15 | 5 | — | — | — | — | — |
Wind waves Height (m) Direction Period (s) | — | — | — | — | — | — | — | — | — | — | — | NE 3 | — | N 7 | N 4 | N 9 | N 4 | N 5 | N 6 | N 7 | N 8 |
| kJ | — | — | — | — | — | — | — | — | — | — | — | 2 | — | 34 | 10 | 52 | 18 | 73 | 125 | 233 | 323 |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 25 | 1 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 650 | 650 | 608 | 650 | 608 | 765 | 765 | 608 |
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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