| Value |
Day
|
Night |
Effect |
| 1 |
|
 |
Fine , clear and very sunny. No wind.Possible problems with sunshine obscuring visibility during day. Night temperatures very cold. Moonlight very strong. |
| 2 |
|
 |
Clear and bright. Moonlight interrupted by the odd cloud. |
| 3 |
|
 |
Light cloud. Slight breeze. |
| 4 |
|
 |
Sunny intervals. Light wind. |
| 5 |
|
 |
Overcast. Light wind. |
| 6 |
|
 |
Cloudy. Medium wind. Seas unstable. Hydrofoils unable to 'fly'. Light craft up to 100 tonnes must return to port. |
| 7 |
|
 |
Showers. Medium wind. Seas becoming rough. Helicopters unable to operate from craft of less than 2,500 tonnes. |
| 8 |
|
 |
Heavy rain. Strong winds. All craft under 2,500 tonnes must find shelter as soon as possible. Craft under 100 t. have 30% chance of sinking. Those under 500 t. have 10% chance of sinking if not in shelter in under 12 hours. All helicopters and VTOL aircraft unable to launch from ships under 5,000 tonnes. |
| 9 |
|
 |
Very rough. No fire possible with sea-skimming missiles, torpedoes or manual guns. Aircraft may only operate from carriers over 30,000 tons or land. |
| 0 |
|
 |
Bloody awful. Mountainous seas, hurricane force winds and wintry rainfall, turning to snow. No air operations possible. Target location reduced to 10km.Only fully automatic guns may fire. All ships under 2,500 tons stand 10% chance of sinking per 24 hours at sea. All craft under 500 tons sink. |