According to About.com, the acetic acid in vinegar moisturizes and soothes skin that has been sunburned. About.com notes that vinegar also helps keep peeling after a sunburn to a minimum.
Earth Clinic explains that apple cider vinegar contains natural anti-inflammatory properties that help decrease pain. Because apple cider vinegar contains vitamins and minerals, applying it to the skin helps replenish nutrients to the skin so that healing takes place more quickly, according to Earth Clinic.
For relief from sunburn pain, How Stuff Works recommends applying vinegar directly to sunburned areas and rubbing it in. Alternatively, diluted vinegar may be poured into a spray bottle and sprayed onto the affected areas of the skin, according to About.com. About.com cautions against using the spray near the face, however, and instead suggests applying vinegar to the face using cotton balls or a cloth.