Surf Forecasts:
Nanwan Beach (South Bay) surf forecast from 18 Aug 2026:
- Best quality surf: Friday 21 Aug, 5AM (local time) - 11ft (3.5m), 10s period, SW swell with cross-shore winds.
- Most powerful swell: Friday 21 Aug, 5PM (local time) - 11ft (3.5m), 11s period, SW swell with 3,133 kJ wave energy.
- Next surfable swell (1★+): Friday 21 Aug, 5AM (local time) - 11ft (3.5m), 10s period with SW swell.
Best Forecast Surf Conditions for Nanwan Beach (South Bay) this week:
The surf forecast for Nanwan Beach (South Bay) over the next 16 days: The first swell (rated 1 star or higher) is forecast to arrive on Friday (Aug 21) at 5AM. The primary swell is predicted to be 3.5m and 10s period. The wind is predicted to be cross-shore as the swell arrives.
The most powerful waves expected at Nanwan Beach (South Bay) in the next 16 days are 3.5m 11s and forecast to arrive on Friday (Aug 21) at 5PM. Winds are predicted to be cross-shore at the time the swell arrives. The largest open ocean swell (not directed at the beach) is 1.7m 6s period and expected on Tuesday (Aug 18) at 11PM.
| Wave Type | Time (CST) & Date | Wave Height & Period |
|---|---|---|
| Next good surf (1 star+) | 5AM (Fri 21st Aug) | 11ft (3.5m) 10s |
| Best Surf | 5AM (Fri 21st Aug) | 11ft (3.5m) 10s |
| Most Powerful | 5PM (Fri 21st Aug) | 11ft (3.5m) 11s |
Table - best surf conditions forecast for Nanwan Beach (South Bay) over the next 16 days.
The Lowdown
Alright, Rusty here, and I’m looking at the next couple weeks for Nanwan Beach (South Bay). Honestly, it’s a rough start – don’t expect much for the first week. The water is 85°F, which is pretty normal for this time of year.
The first real chance to get wet is Tuesday the 25th. On the morning, we’ve got a 6ft SSW swell, with a light offshore wind from the west. The energy is moderate, and the forecast says good surf. The afternoon holds up with a 6ft SW swell and clean cross-offshore wind. That’s the best of the whole run.
Thursday the 20th sees a jump to 8ft, but the wind is cross-on and it’s messy – marginal at best. Saturday the 22nd has a massive 15ft SW swell, but it’s predicted to be too big for this break. That’s expert territory only.
From the 26th, we get a long-period groundswell from the east, with periods up to 16 seconds. The energy is high, up to 1866, but the wind is mostly diagonal or side-on, and it’s only marginal. The long period might make it tricky at a beach break, but it’s worth a look if you’re experienced.
From the 30th of August into September, strong winds blow it out. There’s a 13ft pulse on the 1st of September, but with 28 mph cross winds, it’s a kite surfer’s dream, not a paddler’s.
Bottom line: plan for Tuesday the 25th. The rest is either blown out, too big, or too marginal. Not a classic, but we’ll take what we can get.
Rusty, signing off.
Short Range ForecastHeavy rain (total 116mm), heaviest during Wed night. Warm (max 29°C on Wed morning, min 26°C on Wed night). Mainly fresh winds. | Days 5-7 Weather SummaryHeavy rain (total 55mm), heaviest during Fri night. Warm (max 29°C on Mon afternoon, min 28°C on Fri night). Mainly strong winds. | ||||||||||||||||||
Wednesday 19 | Thursday 20 | Friday 21 | Saturday 22 | Sunday 23 | Monday 24 | ||||||||||||||
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) | SSW 9 | SSW 8 | SSW 8 | SSW 9 | SSW 9 | SSW 10 | SSW 10 | SW 11 | SW 11 | SW 11 | SW 11 | SW 11 | SW 10 | SW 10 | SW 10 | SW 10 | SW 9 | SW 9 | SW 10 |
Wave Graph  | |||||||||||||||||||
 kJ | 286 | 249 | 306 | 1026 | 1263 | 1697 | 1956 | 2699 | 3133 | 2970 | 2515 | 2125 | 1604 | 1297 | 1162 | 906 | 699 | 606 | 673 |
Wind (km/h) | |||||||||||||||||||
Wind State on-shore cross-onshore cross-shore cross-offshore off-shore glassy | cross | cross | on | cross-on | cross | cross | cross | cross | cross | cross | cross-off | cross-off | cross-off | cross-off | cross-off | cross-off | cross | cross | cross |
High Tide | 10:34PM0.92m | 10:51AM0.58m | 11:17PM0.93m | 12:03PM0.47m | 00:13AM0.94m | 1:28AM0.95m | 2:47AM0.98m | 3:51AM1.03m | 6:41PM0.54m | 4:42AM1.09m | |||||||||
Low Tide | 5:35AM0.39m | 3:49PM0.42m | 7:25AM0.40m | 3:28PM0.44m | 9:52AM0.36m | 11:01AM0.29m | 11:37AM0.24m | 12:05PM0.19m | 9:07PM0.52m | ||||||||||
 |  |  | |  | | |  | | | | | | | | | | | | |
 | — | 5:35 | — | — | 5:35 | — | — | 5:35 | — | — | 5:35 | — | — | 5:37 | — | — | 5:37 | — | — |
 | 6:24 | — | 6:24 | — | — | 6:23 | — | — | 6:22 | — | — | 6:22 | — | — | 6:21 | — | — | 6:21 | — |
mm | 2 | — | — | 36 | 25 | 16 | 21 | 9 | 7 | 15 | 8 | 3 | 5 | 4 | 4 | 8 | 3 | 5 | 16 |
Temp °C | 28 | 29 | 29 | 28 | 27 | 27 | 27 | 28 | 28 | 28 | 28 | 28 | 28 | 28 | 28 | 28 | 28 | 29 | 28 |
Feels °C | 27 | 30 | 30 | 32 | 29 | 29 | 29 | 29 | 28 | 28 | 28 | 27 | 28 | 28 | 27 | 29 | 29 | 29 | 30 |
Swell 1 Height (m) Direction Period (s) | SSW 9 | SSW 8 | SSW 8 | SSW 9 | ENE 8 | SSW 10 | NE 8 | ENE 8 | ENE 9 | — | — | ESE 10 | ESE 10 | ESE 10 | SW 10 | SW 10 | SW 9 | SW 9 | SW 10 |
| kJ | 286 | 249 | 306 | 816 | 43 | 1697 | 18 | 7 | 7 | — | — | 10 | 20 | 19 | 1162 | 906 | 699 | 606 | 673 |
Swell 2 Height (m) Direction Period (s) | ESE 10 | ENE 10 | NE 9 | ENE 9 | SE 9 | ENE 8 | — | — | — | — | — | E 14 | — | — | ESE 10 | ESE 9 | ESE 9 | SE 9 | SE 8 |
| kJ | 10 | 37 | 22 | 62 | 13 | 26 | — | — | — | — | — | 4 | — | — | 18 | 17 | 16 | 21 | 24 |
Swell 3 Height (m) Direction Period (s) | SE 8 | ESE 10 | SSE 8 | — | — | — | — | — | — | — | — | — | — | — | E 16 | NE 9 | E 12 | ENE 11 | ENE 10 |
| kJ | 2 | 10 | 13 | — | — | — | — | — | — | — | — | — | — | — | 5 | 3 | 12 | 11 | 10 |
Wind waves Height (m) Direction Period (s) | ENE 6 | ENE 7 | E 6 | SSW 9 | SSW 9 | — | SSW 10 | SW 11 | SW 11 | SW 11 | SW 11 | SW 11 | SW 10 | SW 10 | — | — | — | — | — |
| kJ | 197 | 93 | 41 | 1026 | 1263 | — | 1956 | 2699 | 3133 | 2970 | 2515 | 2125 | 1604 | 1297 | — | — | — | — | — |
Nearest Offshore or Glassy | |||||||||||||||||||
Distance (km) | 996 | 316 | 79 | 42 | 148 | 14 | 148 | 148 | 316 | 316 | 348 | 442 | 348 | 348 | 348 | 316 | 316 | 42 | 14 |
Best forecast wave conditions in South Taiwan | |||||||||||||||||||
Best forecast wave conditions in Taiwan | |||||||||||||||||||
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Information about the Nanwan Beach (South Bay) Surf forecast
The above surf forecast table for Nanwan Beach (South Bay) provides essential information for determining whether the surfing conditions will be good over the next 16 days. A general guide to surfing at Nanwan Beach (South Bay) can be found by selecting the local surf guide option on the grey menu. Our Nanwan Beach (South Bay) 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 (Nanwan Beach (South Bay)) 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 Nanwan Beach (South Bay) 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.
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