Skin damage: environmental risk factors

The following factors in the environment can increase your risk of skin damage from the sun:

• The time of day: avoid being outside from 11:00 to 15:00, when the sun is highest in the sky.
• The time of year: the risk of skin damage is highest in the summer months, but skin damage can occur throughout the year.
• The geographical latitude: the risk is greater the closer you are to the equator.
• Cloud cover: the risk is greatest on a cloudless day. Note, however, that heavy cloud removes only about 50% to 90% of UV radiation.
• Reflection: the UV risk is greatest near reflecting surfaces, such as water and snow.
• Wind and water: don't be fooled by the cooling effect of wind and water – it doesn't reduce the risk.
• Amount of sky visible: the risk is greatest when lots of sky can be seen.

Source:
Hawk, J.L.M. McGregor, J. (2000-2005) Understanding your skin: sunlight & skin cancer. Family Doctor Publications.