Posted by: suiram on Apr-16-12 11:09 AM (EST)
Very rough estimations -
Significant Wave Height is, roughly, twice the average wave height.
1 in 10 waves, roughly, will be at the Significant Wave Height and above.
What is the point? - if you go for a paddle, and the waves don't seem very big for the forecast, don't go cursing NOAA, just wait and see.
Also, when surfing waiting is the name of game - the bigger waves will come, you only need to wait.
Wikipedia has a decent overview