- Detroit heat wave expected to continue into the weekend, with an air quality advisory for ozone issued for Friday.
- Overnight temperatures have remained relatively high this week, increasing the risk for those who are vulnerable to heat illness, including children, those 65 or older and people with chronic health conditions.
- A new report shows that climate change increased the number of nights above 68 degrees in Detroit by 18 between 2018 and 2023.
The Detroit heat wave that baked the city this week is likely to continue into the weekend, with temperatures peaking in the mid to upper 90s on Saturday, although the humidity could make it feel hotter.
Relatively high overnight temperatures in Detroit have posed a special risk for those who lack air conditioning or are vulnerable to heat illness, including children, those 65 or older and people with chronic health conditions. A new report shows that human caused climate change increased the number of nights of 68 degrees or above in Detroit by 18 between 2018 and 2023.
The National Weather Service advises residents to drink plenty of fluids, stay out of the sun and in an air-conditioned space if possible, and check in on relatives and neighbors. The city of Detroit has made recreation centers and libraries available for cooling this week, although some of these locations may be closed on Saturday.
Sunshine and heat are also driving ozone formation, with the state issuing air quality advisories for ozone on Thursday and Friday. This poses a risk for those with asthma, which will be worse during the hottest part of the day.
Nights are getting hotter, posing a health risk
While days were hot this week, the relatively high nighttime temperatures, which haven’t dipped below 71 F since Sunday, may be more concerning. Temperatures can stay higher in cities because of the urban heat island effect or the tendency of impervious surfaces like roads, buildings and other infrastructure to trap heat and warm the surrounding area. This effect can be more pronounced at night, adding to the risk of extreme heat.
Nighttime temperatures have increased more quickly than daytime temperatures, according to Climate Central’s “Sleepless Nights” report, which found Detroit was among the Michigan cities with the highest number of nights with temperatures of 68 F or above attributable to climate change.
Experts warn that high overnight temperatures can be especially dangerous during a heat wave because the body doesn’t have a chance to cool down, raising the risk of heat illness or death.
Research shows that sleep quality declines as temperatures rise, with low-income and elderly people reporting the largest effects. A lack of sleep is associated with many physical and mental health issues, including cardiovascular disease, diabetes, obesity and depression.
When will the Detroit heat wave end?
Detroit may not get a break from the high overnight temperatures until Sunday, according to Brian Cromwell, a meteorologist with the National Weather Service. He said overnight temperatures should fall into the low 60s Sunday night, but the NWS forecasts high temperatures will remain in the 80s or 90s early next week.
"We're expecting storms to pop up throughout the rest of the week into the weekend," Cromwell said, noting that these could be severe. Storms and strong winds on Wednesday evening knocked out power to DTE Energy customers, creating a risk for those depending on fans and air conditioning to stay cool.
The National Oceanic and Atmospheric Association Climate Prediction Center forecasts the heat could continue longer-term. It suggests a slightly above-average likelihood of high temperatures and precipitation in southern Michigan from June 26-30.
Air quality remains a concern
Detroit saw several days this week where ozone levels climbed into the Air Quality Index's "unhealthy for sensitive" groups range.
Ozone forms when cars, factories and other sources emit volatile organic compounds (VOCs) and nitrogen oxides (NOX) in the presence of heat and sunlight. Chemical reactions between the pollutants create ozone, which is more likely to reach dangerous levels on hot and sunny days. Ozone pollution can cause respiratory problems and increase the frequency of asthma attacks.
Ozone poses less of a problem indoors, as long as windows and doors are closed, because it reacts with building materials, resulting in lower ozone levels. Alec Kownacki, a meteorologist with the Michigan Department of Environment, Great Lakes, and Energy’s Air Quality Division, recommended those with asthma stay inside during the hottest part of the day. Kownacki said a shift to more northerly winds this weekend could help clear the air.
"The heat's still going to be there, but northerly winds traditionally bring in cleaner air and wash away some of the pollutants that come up from the south," he said.
EGLE cautioned residents to avoid activities that contribute to ozone formation, such as refueling vehicles and using gas-powered lawn equipment or charcoal lighter fluid. Kownacki advised people not to overexert themselves during the heat and drink lots of water. Experts say that spending even just a few hours in air conditioning during a heat wave can help a person’s body stay cool when they go back into the heat.