No relief from the heat as many US cities will see record overnight temperatures

July 13, 2026 - 20:33

Record-breaking overnight temperatures are expected to hit dozens of U.S. cities this week, turning what is usually a cooling period into a persistent health hazard. Meteorologists warn that the lack of nighttime relief is making the current heat wave particularly dangerous, especially for vulnerable populations without access to air conditioning.

In many regions, the mercury is not expected to drop below 80 degrees Fahrenheit after sunset, a threshold that experts say prevents the human body from recovering from daytime heat exposure. Cities like Phoenix, Las Vegas, and Miami are bracing for some of the highest minimum temperatures ever recorded for this time of year. The National Weather Service has issued excessive heat warnings stretching from the Southwest through the Gulf Coast and into parts of the Midwest.

The danger lies in the cumulative effect. When temperatures stay high through the night, the body cannot cool down, leading to increased risk of heat exhaustion, heat stroke, and even death. Emergency rooms in several states have reported a spike in heat-related illnesses. Public health officials are urging residents to use cooling centers, stay hydrated, and check on elderly neighbors.

Climate scientists point to a long-term trend of warming nights, driven by rising global temperatures and urban heat islands where concrete and asphalt trap heat. This pattern is expected to continue, making these record lows the new normal for many American cities.