
Surf Forecasts:
Mainside surf forecast from 15 Sep 2026:
- Best quality surf: Tuesday 15 Sep, 9PM (local time) - 2.5ft (0.7m), 10s period, E swell with cross-offshore winds.
- Most powerful swell: Sunday 20 Sep, 12PM (local time) - 6.5ft (2.0m), 15s period, E swell with 1,722 kJ wave energy.
- Next surfable swell (1★+): Tuesday 15 Sep, 9PM (local time) - 2.5ft (0.7m), 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 Tuesday (Sep 15) at 9PM. The primary swell is predicted to be 0.7m and 10s period with a secondary swell of 0.7m and 6s. 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 2.0m 15s and forecast to arrive on Sunday (Sep 20) 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 1.1m 5s period and expected on Sunday (Sep 20) at 12AM.
| Wave Type | Time (JST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 9PM (Tue 15th Sep) | 2.5ft (0.7m) 10s |
| Best Surf | 9PM (Tue 15th Sep) | 2.5ft (0.7m) 10s |
| Most Powerful | 12PM (Sun 20th Sep) | 6.5ft (2.0m) 15s |
Table - best surf conditions forecast for Mainside over the next 16 days.
The Lowdown
Alright, listen up. The ocean's got nothing for us right now. For the first few days, the energy is weak—we're talking readings in the 100s (141 Tuesday, 137 Tuesday arvo), and with a pathetic 2ft of swell at a short 9-second interval, it's flat and messy. Stormy feel, cross-off wind but still poor surf. Nothin' to paddle for.
Wednesday and Thursday are more of the same. Swell drops to 2ft, still short period, energy is weak (170 on Wed, 118 on Thu). Mornings are clean with that NE cross-off, but there's no push. It's just plain ordinary.
Then Friday morning, September 18, we get a hint. Swell is 2ft from the N, energy is weak (95), light NE wind makes it glassy. It's the first time we see something above a zero—just "surfable" but very ordinary. Don't get your hopes up.
Saturday the 19th is where the ocean starts to wake up. Morning is small (2ft, 15s period, energy 230), but the afternoon bumps up to 3ft with a 15-second period—that's proper groundswell, and the energy jumps to 449. Now, that sounds good, but the "marginal surf forecast" tag and that long period means the lulls will be long. There might be a clean set, but it's not a reliable one.
Sunday September 20 is where the size shows up but the quality dies. We've got 6ft of swell with a 15-second period, energy at 1611—that's strong. But the wind is fresh from the N at 30 km/h, cross-shore and lumpy. Morning is marginal, arvo is worse: 6ft, fresh cross-onshore breeze, lumpy. This is kite-surfing territory, not a paddle surfing day. Leave the board at home.
Monday the 21st keeps the size but gets messier. 5ft in the morning, ENE swell, 14-second period, energy at 1513, but cross-on wind. By the afternoon, it's 7ft from the NNW with a short 9-second period and a strong cross-onshore breeze. That's a washing machine. Tuesday the 22nd is the same—7ft, cross-on, rain, lumpy. Just ugly.
The rest of that week is smaller but still messy. Wednesday the 23rd has 5ft, Thursday the 24th has 3-4ft, all with cross-onshore winds and choppy conditions. No joy.
Now, there is a pulse late in the game. Tuesday the 29th brings 7ft to 8ft from the NE with a short 7-second period. The energy is moderate (436, 572), but that short period is a killer—it's going to be a jumbled mess. Wednesday the 30th gets bigger: 11ft in the morning, 13ft in the afternoon, but that's way too big for anyone but the experts, and with that short period, it's going to be a beast. Not a standout, more like a "stay safe" warning.
So, if you're looking for the best of the worst, it's that Saturday afternoon the 19th. We're talking 3ft with a 15-second period, light cross-off wind, moderate energy—the only window where it all lines up. But it's marginal. That's the best we're getting.
It's a lean stretch, folks. Keep the wax dry and wait for this to blow through.
Rusty
Short Range ForecastModerate rain (total 15mm), heaviest on Tue afternoon. Warm (max 28°C on Tue morning, min 26°C on Tue night). Wind will be generally light. | Days 4-6 Weather SummarySome drizzle, heaviest during Sat afternoon. Warm (max 28°C on Sat morning, min 26°C on Fri night). Winds increasing (light winds from the NE on Fri morning, fresh winds from the N by Sun afternoon). | ||||||||||||||||||||
Tuesday 15 | Wednesday 16 | Thursday 17 | Friday 18 | Saturday 19 | Sunday 20 | Monday 21 | |||||||||||||||
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 9 | E 10 | E 10 | E 10 | NNW 7 | N 7 | E 9 | E 9 | N 7 | N 8 | N 7 | N 6 | E 15 | E 15 | E 14 | E 15 | E 15 | E 14 | ENE 14 | NNW 9 | NNW 9 |
Wave Graph | |||||||||||||||||||||
81 | 88 | 89 | 90 | 62 | 72 | 41 | 41 | 51 | 40 | 34 | 13 | 170 | 367 | 775 | 1513 | 1699 | 1334 | 939 | 645 | 960 | |
Wind (km/h) | |||||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross | cross-off | cross-off | cross-off | cross | cross-off | cross-off | cross | cross-off | cross-off | cross | cross | cross | cross-off | cross-off | cross | cross-on | cross-on | cross-on | cross-on | cross-on |
High Tide | 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 | 5:12PM1.60m | ||||||||
Low Tide | 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 | 9:28AM0.81m | 10:42PM1.30m | ||||||||
6:13 | — | — | 6:13 | — | — | 6:15 | — | — | 6:15 | — | — | 6:15 | — | — | 6:16 | — | — | 6:16 | — | — | |
— | 6:34 | — | — | 6:32 | — | — | 6:31 | — | — | 6:30 | — | — | 6:30 | — | — | 6:28 | — | — | 6:27 | — | |
mm | 1 | 3 | 3 | 2 | 3 | 2 | — | 1 | — | — | — | — | — | 1 | — | — | — | — | — | — | — |
Temp °C | 28 | 28 | 27 | 27 | 27 | 27 | 27 | 27 | 27 | 27 | 27 | 27 | 28 | 28 | 27 | 27 | 27 | 26 | 26 | 27 | 26 |
Feels °C | 31 | 31 | 30 | 29 | 29 | 29 | 30 | 29 | 30 | 31 | 29 | 29 | 31 | 29 | 28 | 26 | 25 | 22 | 23 | 23 | 23 |
Swell 1 Height (m) Direction Period (s) | E 9 | E 10 | E 10 | NNW 6 | NNW 7 | E 9 | N 6 | E 9 | N 7 | N 8 | N 7 | ESE 9 | E 15 | E 15 | E 14 | E 15 | E 15 | E 14 | ENE 14 | ENE 14 | ENE 14 |
81 | 88 | 89 | 40 | 54 | 61 | 39 | 41 | 51 | 40 | 34 | 28 | 170 | 367 | 775 | 1513 | 1699 | 1334 | 939 | 624 | 290 | |
Swell 2 Height (m) Direction Period (s) | NNW 6 | NNW 6 | N 6 | E 10 | E 9 | ENE 14 | E 9 | ENE 13 | E 9 | E 9 | E 9 | N 6 | ESE 10 | ENE 11 | S 8 | S 8 | S 8 | S 8 | S 8 | S 8 | S 8 |
32 | 37 | 31 | 90 | 62 | 40 | 41 | 34 | 38 | 25 | 24 | 13 | 33 | 47 | 5 | 1 | 5 | 5 | 5 | 1 | 1 | |
Swell 3 Height (m) Direction Period (s) | E 13 | E 12 | SW 8 | ENE 14 | ENE 14 | SE 9 | ENE 14 | N 6 | ENE 13 | ENE 12 | ENE 12 | N 9 | ENE 11 | ESE 9 | N 9 | — | — | — | — | — | SE 10 |
28 | 12 | 2 | 40 | 37 | 3 | 38 | 7 | 34 | 30 | 14 | 6 | 25 | 29 | 13 | — | — | — | — | — | 4 | |
Wind waves Height (m) Direction Period (s) | — | — | — | — | — | N 7 | — | N 6 | — | — | — | NNE 3 | N 7 | N 7 | NE 5 | NNE 6 | N 6 | N 7 | NNW 8 | NNW 9 | NNW 9 |
— | — | — | — | — | 72 | — | 20 | — | — | — | 3 | 35 | 35 | 67 | 98 | 139 | 341 | 574 | 645 | 960 | |
Nearest Offshore or Glassy | |||||||||||||||||||||
Distance (km) | 1 | 9 | 0 | 1 | 9 | 9 | 10 | 1 | 0 | 0 | 41 | 13 | 27 | 27 | 27 | 650 | 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.










