Beaufort Scale
Flags.
The wind is often stronger on other parts of the water than at the club and there may be factors other than indicated wind speed which need to be taken into consideration before you go sailing.
Flags are displayed to indicate overall sailing conditions. If the flag is anything other than Green there are restrictions on the water.
A full description of the flag system can be seen here on the Safety On The Water page.
The Duty Coxswain is always available to give advice on conditions across the water.