Surf Forecasts:
Mainside surf forecast from 4 Sep 2026:
- Best quality surf: Saturday 5 Sep, 9PM (local time) - 3.5ft (1.0m), 8s period, NW swell with offshore winds.
- Most powerful swell: Saturday 5 Sep, 9AM (local time) - 7.5ft (2.3m), 11s period, NW swell with 1,246 kJ wave energy.
- Next surfable swell (1★+): Saturday 5 Sep, 9PM (local time) - 3.5ft (1.0m), 8s period with NW 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 (Sep 05) at 9PM. The primary swell is predicted to be 1.0m and 8s period with a secondary swell of 0.8m and 7s. The wind is predicted to be offshore as the swell arrives.
The most powerful waves expected at Mainside in the next 16 days are 2.3m 11s and forecast to arrive on Saturday (Sep 05) at 9AM. Winds are predicted to be cross-onshore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.6m 8s period and expected on Saturday (Sep 05) at 12PM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 9PM (Sat 5th Sep) | 3.5ft (1.0m) 8s |
| Best Surf | 9PM (Sat 5th Sep) | 3.5ft (1.0m) 8s |
| Most Powerful | 9AM (Sat 5th Sep) | 7.5ft (2.3m) 11s |
Table - best surf conditions forecast for Mainside over the next 16 days.
The Lowdown
Alright, this is Rusty, and I’m looking at the next 16 days for Mainside. It’s a reef break, and it’s exposed to the north, so we’re mostly looking for that N to NW energy to get in here.
Honestly, the outlook is a rough one. We’ve got a huge gap with no real surf to speak of. It’s not until the afternoon of the 14th of September that we finally see something that might be worth a paddle. That’s a long, dry spell of nearly two weeks. The swell is just too small, or the wind is trashing what little energy there is.
The one real standout, and I mean the *only* one, shows up on the afternoon of the 14th. We get a bump of swell rolling in from the east at 4ft, with a short period of 8 seconds. The wind is offshore from the ESE, which is clean for this spot. The combined wave energy is moderate (205). The water temperature is 83°, which is about normal for this time of year. It’s not going to be epic, but it’s the only window where the conditions align for a surfable wave. Since it’s a reef, a short period swell like this might be a bit crumbly, but offshore wind will help.
Before that, the 5th of September has a massive 10ft NW swell slamming in, but it’s accompanied by a near-gale onshore wind. That’s just a washing machine. Not for paddle surfing—that’s kite territory for sure. The wave energy is huge (1900), but it’s completely blown out.
After the 14th, it drops back into the doldrums. The 16th of September morning has a tiny 2ft east swell with glassy conditions, but it’s just too small to get excited about. It’s a clean, flat pond.
So, bottom line: if you’re desperate for a wave, the afternoon of the 14th of September is your only shot. Mark it down. It’s not going to be world-class, but it’s the only game in town.
Rusty.
Short Range ForecastModerate rain (total 15mm), heaviest on Fri afternoon. Warm (max 28°C on Fri afternoon, min 27°C on Sun night). Winds decreasing (strong winds from the WSW on Fri night, light winds from the NNW by Mon morning). | Days 5-7 Weather SummaryMostly dry. Warm (max 28°C on Mon afternoon, min 26°C on Tue night). Mainly fresh winds. | |||||||||||||||||||
Fri 4 | Saturday 5 | Sunday 6 | Monday 7 | Tuesday 8 | Wednesday 9 | Thursday 10 | ||||||||||||||
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) | NNW 7 | NW 7 | NW 11 | N 10 | WNW 7 | N 10 | NNE 8 | N 6 | NNE 8 | N 10 | N 9 | N 8 | N 9 | N 8 | N 7 | N 7 | N 7 | N 6 | N 8 | N 8 |
Wave Graph  | ||||||||||||||||||||
 kJ | 83 | 169 | 1246 | 326 | 134 | 158 | 184 | 181 | 202 | 279 | 412 | 412 | 404 | 157 | 156 | 126 | 61 | 20 | 48 | 109 |
Wind (km/h) | ||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross-on | cross-on | cross-on | on | off | cross-off | cross | cross | cross | cross-on | cross-on | cross-on | cross | cross-on | cross | cross | cross-off | cross-off | cross-off | off |
High Tide | 11:36PM1.86m | 2:36PM1.53m | 1:00AM1.75m | 4:38PM1.63m | 3:05AM1.74m | 5:34PM1.77m | 4:36AM1.86m | 6:12PM1.90m | 5:37AM2.01m | 6:43PM2.00m | 6:26AM2.14m | 7:12PM2.08m | ||||||||
Low Tide | 5:33PM1.19m | 7:11AM0.62m | 7:06PM1.35m | 8:59AM0.62m | 9:37PM1.34m | 10:29AM0.52m | 11:02PM1.18m | 11:31AM0.41m | 11:53PM0.98m | 12:17PM0.33m | 00:33AM0.78m | 12:56PM0.30m | 1:08AM0.61m | |||||||
 |  | | | |  | | | | |  | | | | | | | | | | |
 | — | — | 6:09 | — | — | 6:09 | — | — | 6:09 | — | — | 6:11 | — | — | 6:11 | — | — | 6:11 | — | — |
 | 6:45 | — | — | 6:45 | — | — | 6:44 | — | — | 6:43 | — | — | 6:42 | — | — | 6:40 | — | — | 6:39 | — |
mm | 3 | 4 | 2 | 1 | 4 | — | — | 1 | — | — | — | — | — | — | — | — | — | — | 2 | — |
Temp °C | 28 | 28 | 28 | 28 | 28 | 28 | 28 | 27 | 28 | 28 | 27 | 27 | 28 | 27 | 27 | 27 | 27 | 28 | 28 | 27 |
Feels °C | 29 | 29 | 29 | 30 | 31 | 29 | 28 | 27 | 30 | 29 | 27 | 27 | 27 | 27 | 26 | 26 | 28 | 30 | 29 | 29 |
Swell 1 Height (m) Direction Period (s) | SSW 10 | NW 7 | NW 11 | N 10 | WNW 7 | N 10 | E 6 | E 9 | N 10 | WNW 6 | SSW 8 | SSW 8 | ENE 9 | N 8 | S 8 | S 8 | N 7 | NW 5 | N 8 | N 8 |
| kJ | 275 | 169 | 1246 | 326 | 134 | 158 | 15 | 39 | 51 | 24 | 24 | 22 | 8 | 157 | 11 | 10 | 61 | 4 | 48 | 109 |
Swell 2 Height (m) Direction Period (s) | NNW 7 | S 10 | ESE 7 | W 6 | SSW 8 | WNW 7 | SSW 9 | S 9 | E 8 | NE 11 | ENE 11 | ENE 10 | SW 8 | WNW 6 | SW 8 | SW 8 | S 7 | ESE 10 | ESE 9 | ESE 9 |
| kJ | 83 | 90 | 5 | 109 | 62 | 19 | 25 | 15 | 22 | 59 | 45 | 19 | 10 | 20 | 11 | 3 | 4 | 9 | 8 | 9 |
Swell 3 Height (m) Direction Period (s) | E 9 | ESE 9 | E 10 | SSW 8 | N 11 | S 8 | NW 7 | SW 8 | WNW 7 | SSW 8 | SW 8 | SW 8 | SSE 9 | S 8 | ESE 10 | E 10 | SW 8 | S 7 | NNW 7 | S 7 |
| kJ | 38 | 15 | 8 | 111 | 108 | 36 | 16 | 9 | 9 | 24 | 18 | 16 | 8 | 11 | 10 | 8 | 3 | 4 | 5 | 4 |
Wind waves Height (m) Direction Period (s) | WSW 5 | SW 9 | SSW 9 | SSW 8 | E 4 | ENE 5 | NNE 8 | N 6 | NNE 8 | N 10 | N 9 | N 8 | N 9 | N 8 | N 7 | N 7 | ENE 8 | N 6 | ENE 2 | ESE 4 |
| kJ | 32 | 217 | 124 | 211 | 44 | 97 | 184 | 181 | 202 | 279 | 412 | 412 | 404 | 104 | 156 | 126 | 11 | 20 | 1 | 4 |
Nearest Offshore or Glassy | ||||||||||||||||||||
Distance (km) | 976 | 608 | 15 | 830 | 797 | 9 | 735 | 770 | 735 | 650 | 36 | 39 | 650 | 650 | 608 | 650 | 650 | 59 | 815 | 770 |
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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