The following guidelines for the use of the yellow and red flags have been produced by the CUCBC Safety Advisor, Dr Tom Davies.

A yellow flag will be set at 22.00 hours in preparation for the following morning if, based on the Meteorological Office Cambridge forecast:

• The forecast wind speed is 35 mph or more, or
• The forecast temperature is 0°C or less and the forecast wind speed is 25 mph.

At lighting down minus 30 minutes or 06.00 hours the yellow flag will be confirmed for two hours or lowered. There will be no strict criteria for this as the decision will be taken based on personal observation of conditions at the river. However, suggested guidelines are that the flag should continue to be raised if:

• The wind is "too strong or gusty"
• Current exceeds 5 mph
• Fog does not allow another boat to be seen at 150 metres
• Ice exceeds 2 mm thick more than 1 metre from the bank
• There are conditions where hypothermia would be a risk for crews held static for 10 minutes, based on the forecast criterion.

A red flag will be raised if conditions are unrowable, such as completely frozen or if the water level has risen 1.5 metres or more. Discretion will be exercised when the water level is between 30cm and 1.5m above normal.