Summer heat waves have been the biggest weather-related killers in Wisconsin for more than 50 years, far exceeding tornado and other storm-related deaths. Thousands of Wisconsinites fall ill or are hospitalized for heat-related illnesses each year.
The inside of a vehicle can be especially dangerous. On an 80-degree Fahrenheit day, temperatures inside a vehicle parked in direct sunlight can climb almost 20 degrees in 10 minutes.
Never leave people or pets inside a parked vehicle. Leaving a window cracked is not enough!
Terms used during extreme heat
excessive heat outlook
The outlook is used when the potential for excessive heat exists in the next three to seven days. It provides information to those who need more lead-time to prepare.
This is issued within 12 hours of the start of extremely dangerous heat conditions. The National Weather Service will issue a heat advisory for Wisconsin when the daytime heat index values are 100 to 104. A heat advisory will also be issued if heat indices are 95 to 99 for four consecutive days.
This is issued when conditions are favorable for excessive heat in the next 24 -72 hours.
excessive heat warning
This is issued within 12 hours of the onset of extremely dangerous heat conditions. It will be issued by the National Weather Service when the daytime heat index is 105 or higher during the day and 75 or higher at night for at least a 48-hour period. If heat indices are 100 to 104 for four consecutive days, an excessive heat warning will be issued.
A measure indicating what the temperature feels like to the human body. It is when relative humidity is combined with the air temperature.
How heat index affects you
The Heat Index is an important consideration for comfort. In extreme heat your body works extra hard to maintain a normal temperature, which can lead to serious illness or death. Heat indices 103°F or greater can lead to dangerous heat disorders with prolonged exposure.
80° – 90°F HEAT INDEX
Fatigue is possible with prolonged exposure and/or physical activity.
90° – 103°F HEAT INDEX
Heat stroke, heat cramps, or heat exhaustion possible with prolonged exposure and/or physical activity.
103° – 124°F HEAT INDEX
Heat cramps or heat exhaustion likely, and heat stroke possible with prolonged exposure and/or physical activity.
125°F or higher HEAT INDEX
Heat stroke highly likely
POPULATIONS VULNERABLE TO HEAT
ADULTS OVER 65
They are less aware and adaptable to extreme heat.
People living alone and/or without air conditioning
They may not know when to call for help.
Individuals with disabilities
May not know or realize that they are in danger.
Children under 5
Sensitive to effects of extreme heat and rely on others to keep them cool and hydrated.
People with chronic medical conditions
Medical conditions can worsen the impact of extreme heat
May be unaware of cooling centers and may have limited access to other cooling methods, such as cool showers.
Depend on owner for adequate protection from heat
More likely to become dehydrated and more likely to get heat-related illnesses.
May not have access to current information about heat advisories and health risks associated with extreme heat.