Are Heat Waves Actually Getting More Dangerous?
Philadelphia's new heat emergency named pregnant women high-risk — here's the 'heat plan' doctors recommend.
Key takeaway: Yes — heat waves are getting measurably more frequent and intense, and cities and doctors are responding accordingly. Philadelphia just extended a Heat Health Emergency naming pregnant women as high-risk, and the CDC says even one day of extreme heat can raise pregnancy complications. The protective step experts recommend is…
By Dear Sarah · · Updated
Key takeaways
- Heat waves in the U.S. are becoming more frequent, more intense, and longer-lasting as the planet warms.
- Philadelphia extended a citywide Heat Health Emergency through July 5, 2026, naming pregnant women as a high-risk group alongside older adults and outdoor workers.
- OB-GYN Dr. Keisha Callins says extreme heat can trigger inflammation linked to preterm birth, preeclampsia, and premature rupture of membranes.
- The CDC says as little as one day of heat above the 95th percentile of typical temperature can raise the risk of adverse pregnancy outcomes.
- A simple written 'heat plan' — checking the heat index, hydrating on a schedule, and shifting outdoor time to cooler hours — is the protective step doctors recommend for anyone, not just pregnant women.
If it's felt like the heat is hitting harder this summer, that's not just you being dramatic. Heat waves genuinely are more frequent, more intense, and lasting longer than they used to, and doctors are now telling women — especially pregnant women — to treat extreme heat like a real health risk, not just a discomfort to push through. Philadelphia just extended a citywide Heat Health Emergency through July 5, naming pregnant women alongside older adults and outdoor workers as one of the groups most at risk. That's not fearmongering. It's a pattern showing up in city health departments, in CDC guidance, and in what OB-GYNs are telling their patients right now.
Why is this heat wave different?
Late June into the Fourth of July, a heat dome settled over most of the eastern two-thirds of the country, pushing heat indices to 100–110 degrees across states from Ohio to North Carolina to Washington, D.C. Philadelphia's Department of Public Health declared its emergency on June 30 and extended it twice as the heat index stayed dangerously high. The city's list of high-risk groups reads like a snapshot of who actually bears the weight of a warming planet: people without air conditioning, older adults, small children, outdoor workers, and pregnant women.
That last one surprised me the first time I read it closely, and then it didn't. Dr. Keisha Callins, an OB-GYN and 2025 Climate and Health Equity Fellow at Mercer University School of Medicine, has been explaining why in plain terms: "Heat starts an inflammatory cascade that can lead to premature rupture of membranes and increased hypertensive disorders," including preeclampsia and preterm birth. She's also pointed out something a lot of people miss — "heat can affect the baby in the preconception period and early pregnancy when women don't even know they're pregnant." The CDC backs this up with a number that stopped me: as little as one day of heat above the 95th percentile of typical temperature can raise the risk of a bad pregnancy outcome. Not a whole summer of it. One day.
What doctors are actually telling women to do
Dr. Callins' answer isn't panic, it's a plan. She's encouraging patients to build a written "heat plan" before the worst days hit: check the heat index or your local HeatRisk forecast before you commit to being outside, run errands during the cooler morning hours instead of midafternoon, wear loose and breathable clothing, drink water on a schedule instead of waiting until you're thirsty, and get help fast if you feel dizzy, lightheaded, or overheated. The CDC's version of this is called a Heat Action Plan, and it adds two things worth knowing even if you're not pregnant: check the Air Quality Index too, since bad air and high heat compound each other, and if you take antihistamines or blood pressure medication, know that some of them quietly reduce your body's ability to regulate its own temperature.
Why it matters for you
You don't have to be pregnant for this to be useful information. Women's bodies handle heat differently across a lot of contexts — pregnancy is just the one with the clearest, most-studied data behind it. And even if the biology isn't the reason it lands for you, the caregiving usually is. Women are disproportionately the ones checking on an aging parent during a heat emergency, walking a kid to camp in 98-degree heat, or working a job — retail, food service, home care — that doesn't pause for a heat dome. A heat plan isn't a niche pregnancy tool. It's a five-minute habit that protects whoever you're responsible for, including yourself.
It also connects to something we talk about a lot around here: the small, unglamorous choices that add up to something real. The same logic behind why eco tips matter applies to a heat plan — it's not one dramatic fix, it's a handful of boring, repeatable habits done before you need them. It's the same instinct behind checking how much microplastic one laundry load actually sheds: the planet's problems show up in bodies, not just headlines, and the fixes are almost always smaller and more doable than they sound. And it's the same thread running through the women mapping ocean plastic in the South Pacific — showing up with a plan, even an imperfect one, beats waiting for the crisis to pass.
One thing to try today
Pull up your phone's weather app right now and check tomorrow's heat index, not just the temperature number. If it's high, pick one small adjustment: move your outdoor plans earlier, pack a water bottle you'll actually refill, or text the person you check in on to make sure they have a way to stay cool. That's the whole heat plan. It doesn't need to be more complicated than that to work.
Quote to sit with
"It's the little things citizens do. That's what will make the difference. My little thing is planting trees." — Wangari Maathai
💌 Sarah
Frequently asked questions
Are heat waves getting more dangerous because of climate change?
Yes. Heat domes like the one that hit the eastern two-thirds of the U.S. in late June and early July 2026 are becoming more frequent and intense as average temperatures rise, and cities including Philadelphia have started declaring formal Heat Health Emergencies in response.
Is extreme heat dangerous during pregnancy?
Yes. The CDC and OB-GYNs like Dr. Keisha Callins link heat exposure to preterm birth, stillbirth, low birthweight, and hypertensive disorders including preeclampsia, and note that even a single day of extreme heat can raise risk.
What is a 'heat plan' and do I need one if I'm not pregnant?
A heat plan is a short, written set of steps — checking the heat index, drinking water on a schedule, avoiding peak-heat hours outdoors, and knowing your medications' effect on heat tolerance — that doctors recommend building before a heat wave hits. It's useful for anyone, not just pregnant women, especially if you care for kids, older relatives, or work outdoors.
What cities have declared heat emergencies in 2026?
Philadelphia declared a Heat Health Emergency on June 30, 2026 and extended it twice through July 5 as a heat dome pushed heat indices to 100–110 degrees across much of the eastern two-thirds of the country, including Ohio, North Carolina, and Washington, D.C.
How do I know if a hot day is actually dangerous, not just uncomfortable?
Check your local heat index or HeatRisk forecast rather than just the temperature number. The CDC recommends taking protective action once it reaches the orange level or higher, since humidity and prolonged exposure make a 'hot' day cross into medically risky territory.
Sources
- Pregnant women are at risk of illness and preterm labor. So this OB-GYN suggests a 'heat plan' — Georgia Public Broadcasting
- Philadelphia Heat Health Emergency Extended through Sunday, July 5, 2026 — City of Philadelphia Department of Public Health
- Clinical Overview of Heat and Pregnancy — CDC
- A 'heat dome' is driving dangerous heat across the U.S. into the July 4 weekend — NPR
Keep reading
- How much microplastic does one laundry load actually shed? — One load of laundry can shed 700,000 microfibers. Six low-lift changes that actually keep them out of the water, starting with your next wash.
- A boatful of women is mapping ocean plastic right now — While we're scrolling, a crew of women is sailing the South Pacific tracing plastic back to the brand it came from. Here's the bit that's actually for us.
- Why Eco Tips Matter — Small, consistent eco choices reduce waste, conserve resources, and protect the world we love for future generations.
- Does Creatine Help With Depression? What New Research Shows — A new review of five clinical trials on creatine and depression found real promise — but only in the trials that studied women. Here's the honest read.