On days during the summer months when high temperatures are expected, weather forecasters frequently warn about the dangers of UV and high UV indices. It is not surprising, therefore, that it is a common belief that high ambient air temperatures are a major risk factor for burning. Although the UV index is generally higher on cloudless, hot days compared with cloudy, cool days, reliance should not be placed on ambient temperature alone as a guide to the need for sun protection. This article is protected by copyright. All rights reserved.