Heat Wave - A prolonged period of excessively hot weather, which may be accompanied by high humidity. Temperatures that people from a warmer climate consider normal can be termed a heat wave in a cooler area if they are outside the normal climate pattern for that area. The definition recommended by the World Meteorological Organization is when the daily maximum temperature of more than five consecutive days exceeds the average maximum temperature by 5 degrees C (9 degrees F)
In North America the summers are hot. In Pueblo, Colorado yesterday it was 102 degrees F. and most summers in one or more parts of America experience heat waves. East of the Rocky Mountains these heat waves often combine both high temperatures and humidity, even though some of the worst heat waves have been incredibly dry. Every National Weather Service Forecast Office issues heat related Outlooks, Watches, and Warning/Advisories:
Excessive Heat Outlooks: Excessive heat outlooks are issued when there is potential for an Excessive Heat Event (EHE) within the next three to seven days. An Outlook provides people with information should they need a considerable amount of lead time to prepare for the heat. The people who may need this information include emergency managers, public utility staff members, and public health officials.
Excessive Heat Watches: Excessive heat watches are issued when conditions are favorable for an EHE within the next 24-72 hours. A Watch is used when the risk of a heat wave has increased yet the timing and occurrence remain uncertain. A Watch gives people enough lead time so they can prepare, such as city officials who have EHE mitigation plans in place.
Excessive Heat Warning/Advisories: Excessive heat warning/advisories are issued when an EHE is expected within 36 hours. They are issued when an EHE is happening, is imminent, or is very likely to occur. The warning is used for conditions that present a threat to human life. An advisory is for less serious conditions that cause significant inconvenience or discomfort and - if people do not take caution, may lead to threat to life.
The Decision to Issue Outlooks, Watches or Warning/Advisories
Heat alert procedures are based mainly on Heat Index Values. The Heat Index, at times referred to as the, 'apparent temperature,' is presented in degrees Fahrenheit. The heat Index is a measure of how hot if truly feels when relative humidity is factored in with the actual temperature of the air. For example; if the temperature of the air is 96 degrees F. and the relative humidity is 65%, the heat index is 121 degrees Fahrenheit. The National Weather Service issues alerts when the heat index is expected to rise above 105 degrees for at least two days in a row.
During extremely humid and hot weather, a person's body and its ability to cool itself are affected. When a person's body heats too quickly to cool itself appropriately or when too much salt or fluid is lost through sweating or dehydration, their body temperature rises and heat-related illnesses might develop. Heat-related illnesses may range from heat cramps to heat exhaustion to heat stroke. A heat stroke may even result in death and demands immediate medical attention. Conditions or factors that may make some people more susceptible to heat-related illnesses include:
Sunburn, caused by ultraviolet radiation from the sun, might significantly reduce a person's skin's ability to shed excessive heat. Heat-related illness symptoms, as well as first aid, can include the following:
Heat Cramps: The symptoms of heat cramps include heavy sweating, painful muscle cramps and spasms - commonly in the abdomen and legs. First aid involves giving the person sips of water unless they experience nausea, and applying firm pressure on muscles that are cramping or gently massaging the person's muscles to relieve spasms.
Heat Exhaustion: The symptoms of heat exhaustion include weakness, heavy sweating, a weak pulse, cool, pale and clammy skin, nausea and vomiting, dizziness, muscle cramps, and fainting. First aid involves moving the person to a cooler place, applying wet, cool cloths, removing or loosening the person's clothes, moving the person to a place with a fan or an air conditioner, and offering them sips of water unless they become nauseous or vomit.
Heat Stroke: A heat stroke is a medical emergency. The symptoms of heat stroke include a rapid pulse, an altered mental state, a high body temperature, potential for a throbbing headache, nausea, confusion, shallow breathing, dizziness, as well as unconsciousness. First aid for heat stroke includes -
Remember - a heat stroke really is a severe medical emergency. Seek prompt emergency medical assistance, or get the person to a hospital at once. A delay can be fatal. I know - I experienced a heat stroke and have had epilepsy ever since.
Never, ever leave children, people with disabilities, or your pets in a parked vehicle in hot weather; period. Every year, dozens of children and uncounted numbers of pets who were left in parked vehicles in hot weather die from hyperthermia. Hyperthermia is an acute condition that happens when a body absorbs more heat than it can deal with. Hyperthermia can happen even on a seemingly mild day. Studies have demonstrated that the temperature in a parked car can quickly rise to dangerous levels for children, your pets, and even adults. Leaving the windows slightly open does little to nothing to decrease the rate of heating. The effects can be even more severe on children because their bodies warm at a quicker rate than adults.
Shortwave radiation from the sun heats objects that it strikes. For example, a dark dashboard or seat in a car may quickly reach temperatures in the range of 180 degrees to over 200 degrees. Objects such as steering wheels, dashboards, child seats and so forth in a car then heat adjacent air by conduction and convection and give off long-wave radiation that is very efficient at warming air trapped in vehicles.
The sun's shortwave radiation (yellow in figure below) heats objects that it strikes. For example, a dark dashboard or seat can easily reach temperatures in the range of 180 to over 200 degree F. These objects (e.g., dashboard, steering wheel, child seat) heat the adjacent air by conduction and convection and also give off long-wave radiation (red in figure below) which is very efficient at warming the air trapped inside a vehicle. Hyperthermia deaths happen not only in the summer, they can also happen in spring or fall. What follows are some safety tips:
Specific high-risk groups often experience a disproportionate number of health impacts due to EHE's. The populations that have social, physical, and economic factors and the particular actions that make them at high risk include people who:
The population of at risk people also includes infants who are under the age of one year. While there are a number of methods for estimating the public health threat and impact of EHE's, it is important to understand that the most conservative of these counts only the people who have died as a result of excessive heat as listed on their death certificate. Using this method it was estimated that extreme heat is on average responsible for 182 deaths each year in America. It is very important to watch out for your health and the health of those you care about during high temperatures.
High Temperatures Dangerous For Children
Summer is officially here and temperatures across the nation are soaring. Although the heat wave is welcomed by many after a cold winter, the increase in temperature is especially dangerous for children...
High Temperatures Today
The High Temperatures Today image shows the forecast high temperatures for the current day, color contoured every 10 degrees F.
Climate Impacts on Human Health
Warmer average temperatures will likely lead to hotter days and more frequent and longer heat waves. This could increase the number of heat-related illnesses and deaths.