Total wave height, also known as significant wave height, describes the combined height of the sea and the swell that mariners experience on open waters. The Bureau provides model forecasts of total wave height via the interactive map viewer
The total wave height can be calculated from the separate sea and swell heights using the lookup table below.
Example
If the forecast reads:
Forecast for Monday until midnight
- Winds
- Northwest to southwesterly 15 to 20 knots becoming southwesterly 10 to 15 knots in the late afternoon then tending southeast to southwesterly in the evening.
- Seas
- Up to 1.5 metres.
- Swell
- South to southeasterly 1 to 1.5 metres.
- Weather
- Partly cloudy. 60% chance of showers late this afternoon and evening.
A forecast sea of 1.5m, and a forecast swell of 1.5m, could result in a total wave height of 2.1m.
SWELL HEIGHT (metres) | |||||||||||||
0 | 0.5 | 1.0 | 1.5 | 2.0 | 2.5 | 3.0 | 4.0 | 5.0 | 6.0
| ||||
SEAS or WIND WAVE HEIGHT (metres) | 0.5
|
0.5 |
0.7 |
1.1 |
1.6 |
2.1 |
2.6 |
3.0 |
4.0 |
5.0 |
6.0 | ||
1.0
|
1.0 |
1.2 |
1.4 |
1.8 |
2.2 |
2.7 |
3.2 |
4.1 |
5.1 |
6.1 | |||
1.5
|
1.5 |
1.6 |
1.8 |
2.1 |
2.5 |
2.9 |
3.4 |
4.3 |
5.2 |
6.2 | |||
2.0 |
2.0 |
2.1 |
2.2 |
2.5 |
2.8 |
3.2 |
3.6 |
4.5 |
5.4 |
6.3 | |||
2.5 |
2.5 |
2.6 |
2.7 |
2.9 |
3.2 |
3.5 |
3.9 |
4.7 |
5.6 |
6.5 | |||
3.0 |
3.0 |
3.0 |
3.2 |
3.4 |
3.6 |
3.9 |
4.2 |
5.0 |
5.8 |
6.7 | |||
4.0 |
4.0 |
4.0 |
4.1 |
4.3 |
4.5 |
4.7 |
5.0 |
5.7 |
6.4 |
7.2 | |||
5.0 |
5.0 |
5.0 |
5.1 |
5.2 |
5.4 |
5.6 |
5.8 |
6.4 |
7.1 |
7.8 | |||
6.0 |
6.0 |
6.0 |
6.1 |
6.2 |
6.3 |
6.5 |
6.7 |
7.2 |
7.8 |
8.5 | |||
About the calculation
The table above was calculated using the following formula.
Combined sea and swell height = [(Wind Wave Height)2 + (Swell Wave Height)2+ (Secondary Swell Wave Height)2]1/2
About the values in this table
The Bureau provides forecasts of swell and sea to the nearest 0.5m. To be consistent with this precision, the total wave height values in the above table should be "rounded" to the nearest 0.5m.
