Heat indices to surpass 100 in Metro Detroit on Wednesday: What you need to know

It’ll feel like 105 on Wednesday

Heat Watch Map. (WDIV)

Here comes the heat.

It’s not even really summer yet, but it’s going to feel like the peak of summer this week in Southeast Michigan, with temps pushing into the upper 90s on Wednesday -- here’s more on what to expect from Brandon Roux:

The National Weather Service has placed Metro Detroit under an excessive heat watch starting Wednesday afternoon through Thursday morning. This means the heat and humidity combined will not only help highs reach record levels in the mid-to-upper 90s, but it will feel like 105 degrees or warmer at times. This can lead to heat-related illness very quickly, so be diligent about your children, pets and loved ones.

It’s all about hydration and shade for anyone who must work or play outdoors on Wednesday.

There is a cold front moving through SE Lower Michigan and Southern Ontario Thursday morning, and that will bring a line of showers and storms through our area likely before the sun rises. That front will eventually cool things down, but it will happen slowly -- which means we still have a good shot at seeing 90 degrees on Thursday after those scattered morning rain and thundershowers.

Thursday afternoon will bring a nice sun and cloud mixture. The humidity will become much more comfortable throughout the day and into the Father’s Day weekend.


Schools closing for heat?

Some schools are still in session right now, and some are closing for the day, or closing early. You can track that here as they come in. Detroit is dismissing three hours early, and Dearborn is closing all schools on Wednesday.

How does the heat index work?

From the National Weather Service: The Heat Index is a measure of how hot it really feels when relative humidity is factored in with the actual air temperature. To find the Heat Index temperature, look at the Heat Index Chart above or check our Heat Index Calculator. As an example, if the air temperature is 96°F and the relative humidity is 65%, the heat index--how hot it feels--is 121°F. The red area without numbers indicates extreme danger. 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 2 consecutive days.

NWS also offers a Heat Index chart for areas with high heat but low relative humidity. Since heat index values were devised for shady, light wind conditions, exposure to full sunshine can increase heat index values by up to 15°F. Also, strong winds, particularly with very hot, dry air, can be extremely hazardous.

Chart provides heat index values based on relative humidity and temperature to account for the human body's comfort level. (NWS)

What’s a heat watch?

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.

What precautions can you take?

More from NWS: Heat is one of the leading weather-related killers in the United States, resulting in hundreds of fatalities each year. Heat can be very taxing on the body; check out the heat related illnesses that can occur with even a short period of exposure. Everyone can be vulnerable to heat, but some more so than others. According to The Impacts Of Climate Change On Human Health In The United States: A Scientific Assessment the following groups are particularly vulnerable to heat; check in with friends and relatives who fall in one of these populations, especially if they don’t have air conditioning.

  • Young children and infants are particularly vulnerable to heat-related illness and death, as their bodies are less able to adapt to heat than are adults.
  • Older adults, particularly those with pre existing diseases, take certain medications, are living alone or with limited mobility who are exposed to extreme heat can experience multiple adverse effects.
  • People with chronic medical conditions are more likely to have a serious health problem during a heat wave than healthy people.
  • Pregnant women are also at higher risk. Extreme heat events have been associated with adverse birth outcomes such as low birth weight, preterm birth, and infant mortality, as well as congenital cataracts.

It is NEVER safe to leave a child, disabled person or pet locked in a car, even in the winter. If you have a toddler in your household, lock your cars, even in your own driveway.  Kids play in cars or wander outside and get into a car and can die in 10 minutes! A reported 25 children died in hot cars in 2020. To see the latest information for 2021, go to this link. Deaths routinely are reported as early as April and tragedies continue into December in southern states.

During extremely hot and humid weather, your body’s ability to cool itself is challenged. When the body heats too rapidly to cool itself properly, or when too much fluid or salt is lost through dehydration or sweating, body temperature rises and you or someone you care about may experience a heat-related illness. It is important to know the symptoms of excessive heat exposure and the appropriate responses. The Centers for Disease Control and Prevention (CDC) provides a list of warning signs and symptoms of heat illness, and recommended first aid steps. Some of these symptoms and steps are listed below.

Heat Cramps

Heat cramps may be the first sign of heat-related illness, and may lead to heat exhaustion or stroke.

  • Symptoms: Painful muscle cramps and spasms usually in legs and abdomen and Heavy sweating.
  • First Aid: Apply firm pressure on cramping muscles or gently massage to relieve spasm. Give sips of water unless the person complains of nausea, then stop giving water. Seek immediate medical attention if cramps last longer than 1 hour.

Heat Exhaustion

  • Symptoms: Heavy sweating, Weakness or tiredness, cool, pale, clammy skin; fast, weak pulse, muscle cramps, dizziness, nausea or vomiting, headache, fainting,
  • First Aid: Move person to a cooler environment, preferably a well air conditioned room. Loosen clothing. Apply cool, wet cloths or have person sit in a cool bath. Offer sips of water. If person vomits more than once, Seek immediate medical attention if the person vomits, symptoms worsen or last longer than 1 hour

Heat Stroke

  • Symptoms: Throbbing headache, confusion, nausea, dizziness, body temperature above 103°F, hot, red, dry or damp skin, rapid and strong pulse, fainting, loss of consciousness.
  • First Aid: Call 911 or get the victim to a hospital immediately. Heat stroke is a severe medical emergency. Delay can be fatal. Move the victim to a cooler, preferably air-conditioned, environment. Reduce body temperature with cool cloths or bath. Use fan if heat index temperatures are below the high 90s. A fan can make you hotter at higher temperatures. Do NOT give fluids.

Using a fan to blow air in someone’s direction may actually make them hotter if heat index temperatures are above the 90s. For more information on all of these heat related illnesses, see the Centers for Disease Control and Prevention (CDC) site.


About the Author:

Ken Haddad is the digital content and audience manager for WDIV / ClickOnDetroit.com. He also authors the Morning Report Newsletter and various other newsletters. He's been with WDIV since 2013. He enjoys suffering through Lions games on Sundays in the fall.