Extreme Heat

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.

heat advisory

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.

heat watch

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.

heat index

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

HEAT-related illnesses

Heat-related illnesses are preventable. Learn the symptoms and what to do.

HEAT STROKE

What to look for:
High body temperature (103°F or higher)
Hot, red, dry, or damp skin
Fast, strong pulse
Headache
Dizziness
Nausea
Confusion
Losing consciousness (passing out)
What to do:
Call 911 right away
Move the person to a cooler place
Help lower the person’s temperature with cool cloths or a cool bath
Do not give the person anything to drink

HEAT EXHAUSTION

What to look for:
Heavy Sweating
Cold, pale, and clammy skin
Fast, weak pulse
Nausea or vomiting
Muscle cramps
Tiredness or weakness
Dizziness
Headaches
Fainting
What to do:
Move to a cool place
Loosen your clothes
Put cool, wet cloths on your body or take a cool bath
Sip water
Get medical help right way if you experience vomiting, symptoms get worse, or symptoms last longer than one hour

HEAT CRAMPS

What to look for:
Heavy sweating during intense exercise
Muscle pain or spasms
What to do:
Stop physical activity and move to a cool place
Drink water or a sports drink
Wait for cramps to go away before doing more physical activity
Get medical help right away if cramps last longer than one hour, you’re on a low-sodium diet, or if you have heart problems.

sunburn

What to look for:
Painful, red, and warm skin
Blisters on skin
What to do:
Stay out of sun until sunburn heals
Put cool cloths on sunburns or take cool bath
Put moisturizing lotion on sunburned areas
Do not break blisters

heat rash

What to look for:
Red clusters of small blisters that look like pimples (usually on the neck, chest, groin, or in elbow creases)
What to do:
Stay in a cool, dry place
Keep the rash dry
Use powder (like baby powder) to soothe the rash

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

HOMELESS

May be unaware of cooling centers and may have limited access to other cooling methods, such as cool showers.

PETS

Depend on owner for adequate protection from heat

OUTDOOR WORKERS

More likely to become dehydrated and more likely to get heat-related illnesses.

Non-English speakers

May not have access to current information about heat advisories and health risks associated with extreme heat.

What to do before AND during EXTREME HEAT

BEFORE

Do not rely on a fan as your primary cooling device. Fans create air flow, but do not reduce body temperatures or prevent heat-related illnesses
Identify places in your community to get cool, such as libraries, shopping malls, or contact your local health department to find a cooling center in your area.
Cover windows with drapes or shades
Weather-strip doors and windows
Use window reflectors specifically designed to reflect heat back outside.
Use a powered attic ventilator or attic fan to clear out hot air in the attic
Install window air conditioners and insulate around them.
If you are unable to afford cooling costs, weatherization, or energy-related home repairs, contact the Low Income Home Energy Assistance Program (LIHEAP) for help.

DURING

Take care of your body.
Drink plenty of water. Make sure you drink before feeling thirsty. By the time you feel thirsty, you are already behind in fluid replacement. When working in the heat, drink one cup (8 ounces) of water every 15-20 minutes.
Limit alcohol consumption. Drinking beer and alcoholic beverages cause further body dehydration.
It is not recommended to take salt tablets. In most cases, salt can be replaced by eating normal meals and snacks throughout the day. Do not skip meals.
Cover windows to keep the sun from shining in.
If you have an air conditioner, use it. If you do not have one and the temperature is above 95 °F, you should go to a community cooling center because a fan will no longer prevent heat-related illnesses at this temperature.
Pace yourself. Cut down on exercise during the heat. If you are not accustomed to working or exercising in a hot environment, start slowly and pick up the pace gradually. If exertion in the heat makes your heart pound and leave you gasping for breath, STOP all activity. Get into a cool area or shade and rest.
Wear sunscreen. Sunburn affects your body’s ability to cool down. Put on a sunscreen of SPF 15 or higher 30 minutes before going outside and reapply as the package directs. Consider a wide-brimmed hat and sunglasses as well.
Consider pet and livestock safety.
Keep pets hydrated by providing clean and cool drinking water
Provide shade with good air flow.
Protect their paws. Place the back of your hand on the ground for five seconds. If it’s too hot for your skin, it’s too hot for your pet’s paw pads. Consider walking your pet in the early morning or in the evening when the asphalt has cooled down.
Do not leave them in a car. Even with the windows cracked, the interior temperature can become deadly in minutes.
Check on others.
Check on older, sick, or frail people who may need help responding to heat.
Don’t leave electronic equipment in hot cars
Make sure rooms are well vented if you are using volatile chemicals.

Additional Resources

Wisconsin Department of Health Services – Extreme Heat Toolkit:

https://www.dhs.wisconsin.gov/publications/p0/p00632.pdf

National Weather Service Heat Safety Tips:

https://www.weather.gov/safety/heat