Excessive heat creates health threat
National Weather Service
North American summers are hot; most summers see heat waves in one or more parts of the United States. East of the Rockies, summers tend to combine both high temperatures and high humidity, although some of the worst heat waves have been catastrophically dry.
NOAA's watch, warning and advisory products for extreme heat
Excessive heat outlooks are issued when the potential exists for an excessive heat event in the next three to seven days. An Outlook provides information to those who need considerable lead time to prepare for the event, such as public utility staff, emergency managers and public health officials. See the mean heat index and probability forecasts maps.
Excessive heat watches are issued when conditions are favorable for an excessive heat event in the next 24 to 72 hours. A Watch is used when the risk of a heat wave has increased but its occurrence and timing is still uncertain. A Watch provides enough lead time so that those who need to prepare can do so, such as city officials who have excessive heat event mitigation plans.
Excessive heat warning/advisories are issued when an excessive heat event is expected in the next 36 hours. These products are issued when an excessive heat event is occurring, is imminent, or has a very high probability of occurring. The warning is used for conditions posing a threat to life. An advisory is for less serious conditions that cause significant discomfort or inconvenience and, if caution is not taken, could lead to a threat to life.
How forecasters decide whether to issue excessive heat products
To find the Heat Index temperature, look at the Heat Index chart. As an example, if the air temperature is 96°F and the relative humidity is 65 percent, the heat index--how hot it feels -- is 121°F. The National Weather Service will initiate alert procedures when the Heat Index is expected to exceed 105°-110°F (depending on local climate) for at least two consecutive days.
Hazards of excessive heat
Heat-related illnesses can range from heat cramps to heat exhaustion to more serious heat stroke. Heat stroke can result in death and requires immediate medical attention.
Factors or conditions that can make some people more susceptible to heat-related illnesses include age (older adults and young children), obesity, fever, heart disease, mental illness, poor circulation, prescription drug and alcohol use, and sunburn. Sunburn, caused by ultraviolet radiation from the sun, can significantly retard the skin's ability to shed excess heat.
Heat-related illness symptoms and first aid
Heat stroke (or sunstroke)
Heat stroke is a severe medical emergency. Summon emergency medical assistance or get the victim to a hospital immediately. Delay can be fatal.
Never leave children, disabled adults or pets in parked vehicles