What Is Overnight Heat? Overnight heat occurs when temperatures remain unusually high during the nighttime hours, providing little relief from hot daytime conditions. Instead of cooling substantially after sunset, temperatures remain elevated through the night and into the early morning. Warm nights are particularly important during heat waves and periods
What Is Dry Heat? Dry heat describes hot weather that occurs when atmospheric humidity is relatively low. During dry heat, the air contains less moisture than during humid hot weather, allowing sweat to evaporate from the skin more efficiently. This can make dry heat feel different from humid heat, but
What Is a Hot Spell? A hot spell is a period of unusually warm or hot weather that lasts for several days but may be shorter, less intense or less persistent than a major heat wave. Temperatures during a hot spell are typically noticeably above normal for a particular location
What Is a Heat Wave? A heat wave is a prolonged period of unusually hot weather that lasts for several consecutive days and is significantly warmer than normal for a particular location and time of year. Heat waves may involve high daytime temperatures, warm overnight temperatures, elevated humidity or a
What Is Extreme Heat? Extreme heat occurs when temperatures become unusually high for a particular location and time of year, creating conditions that can place significant stress on the human body, infrastructure and the environment. Extreme heat can occur during a prolonged heat wave or as a shorter period of