However, all skin types can develop sunburn.Fitzpatricks skin phototypes:

Type 0: Albino
Type I: Pale white skin, burns easily, does not tan
Type II: White skin, burns easily, tans with difficulty
Type III: White skin, may burn but tans easily
Type IV: Light brown/olive skin, hardly burns, tans easily
Type V: Brown skin, usually does not burn, tans easily
Type VI: Black skin, very unlikely to burn, becomes darker with UV radiation exposureAge also affects how skin reacts to sun. Children younger than six and adults older than sixty are more sensitive to sunlight.There are certain genetic conditions, for example xeroderma pigmentosum, that increase a persons susceptibility to sunburn and subsequent skin cancers. These conditions involve defects in DNA repair mechanisms which in turn decreases the ability to repair DNA that has been damaged by UV radiation. Medications
The risk of a sunburn can be increased by pharmaceutical products that sensitize users to UV radiation. Certain antibiotics, oral contraceptives, antidepressants, acne medications, and tranquillizers have this effect. UV intensity
The UV Index indicates the risk of getting a sunburn at a given time and location. Contributing factors include:
The time of day. In most locations, the suns rays are strongest between approximately 10 am and 4 pm daylight saving time. Cloud cover. UV is partially blocked by clouds; but even on an overcast day, a significant percentage of the suns damaging UV radiation can pass through clouds. Proximity to reflective surfaces, such as water, sand, concrete, snow, and ice. All of these reflect the suns rays and can cause sunburns. The season of the year.
Unlike phototoxic reactions which resemble exaggerated sunburns, photoallergic reactions can cause intense itching and can lead to thickening of the skin. Phytophotodermatitis: UV radiation induces inflammation of the skin after contact with certain plants (including limes, celery, and meadow grass). Causes pain, redness, and blistering of the skin in the distribution of plant exposure. Polymorphic light eruption: Recurrent abnormal reaction to UVR. It can present in various ways including pink-to-red bumps, blisters, plaques and urticaria. Solar urticaria: UVR-induced wheals that occurs within minutes of exposure and fades within hours. Other skin diseases exacerbated by sunlight: Several dermatologic conditions can increase in severity with exposure to UVR. These include systemic lupus erythematosus (SLE), dermatomyositis, acne, atopic dermatitis, and rosacea.Additionally, since sunburn is a type of radiation burn, it can initially hide a severe exposure to radioactivity resulting in acute radiation syndrome or other radiation-induced illnesses, especially if the exposure occurred under sunny conditions. For instance, the difference between the erythema caused by sunburn and other radiation burns is not immediately obvious. Symptoms common to heat illness and the prodromic stage of acute radiation syndrome like nausea, vomiting, fever, weakness/fatigue, dizziness or seizure can add to further diagnostic confusion. Prevention
The most effective way to prevent sunburn is to reduce the amount of UV radiation reaching the skin.