As heat-trapping greenhouse gases increase the global average temperature, we are experiencing higher average temperatures and more extreme and record-breaking heat events. This is most apparent in the summertime since it’s the hottest time of the year.
A Climate Central analysis evaluated 51 years of summer temperature data in 246 U.S. locations. Results show an overall warming trend for the summer season, with:
- Rising average temperatures: About 95% (233) of the locations had an increase in their average summer temperature, with 50% (122) of those increasing by 2°F or more.
- A fast-warming Western region and Texas: Nine out of the top ten fastest-warming summer locations were located in the Western U.S. and Texas, with Reno, Nev. (10.6°F), Las Vegas (5.6°F), and El Paso, TX (5.5°F) in the lead.
- Warmer summer nights: Summer night temperatures increased by 2°F or more in 61% of the locations.
- And more extremely hot days: 38% of locations reported, on average, at least one additional week of extremely hot temperatures annually (compared to 1970) and 59% have reported an annual increase of at least three days. The largest change is in Miami with 79 additional days above a sizzling 90°F.
Extreme heat is the deadliest kind of hazardous weather to humans and has many negative consequences to human health:
- Extreme heat can increase heat-related illnesses in vulnerable populations. This includes seniors, younger children, and people without air conditioning.
- Summer heat can contribute to poor air quality by trapping harmful pollutants close to the Earth’s surface and creating ground-level ozone. These pollutants can inflate respiratory problems in people with asthma and other lung diseases.
- In areas without air conditioning, warmer nights can cause health issues by not letting our bodies cool off and recover after intense heat events. One study also reveals that warmer nights can disrupt our sleeping patterns.
- Cities can get much hotter than surrounding suburban and rural areas because they have more heat-absorbing surfaces and materials. Studies have found that this “urban heat island” effect disproportionately affects Black and immigrant communities, which typically have less shade-covering trees than whiter areas.