Monday's ultraviolet index level in the Los Angeles area will be 11, an extreme level that is rarely seen, according to the National Weather Service.
The 11 rating is unusual and indicates that the UV exposure expected at noon, when the sun's rays are at their strongest, could cause burns to fair-skinned people.
A reading of 0-2 indicates a minimal exposure level, and very fair-skinned people could become sunburned in 30 minutes if not properly protected.
A reading of 3-4 is considered a low exposure level, reducing the danger range for those with fair complexions to 15-20 minutes if not protected.
A moderate exposure level of 5-6 indicates that a person with a fair complexion could be safe from sun burn for 10-12 minutes, unless protected.
A high exposure level reading of 7-9 means that a person could be sunburned in 7-8 minutes.
A very high exposure level reading of 10, or greater, means a fair-skinned person could suffer a sunburn in about four minutes if not protected.
Ultraviolet radiation is blamed for a host of health problems, including skin cancer and cataracts.