Disaster Discourse: The Hagerty Blog

Extreme Heat Wave Persists, Fueling Record-Breaking Temperatures for Millions

TUESDAY, JULY 25, 2023, AS OF 3:00 PM EST

An extreme heat wave is continuing to impact large portions of the United States (US), as more than 46 million Americans are currently facing heat alerts as of Tuesday, July 25. According to the National Oceanic and Atmospheric Administration (NOAA), the US has set or tied over 13,000 high-temperature records so far this year, with nearly 2,000 occurring within the month of July. On July 24, residents in Phoenix, Arizona, experienced their 24th consecutive day of 110-degree or higher temperatures, breaking a nearly 50-year record. At this rate, forecasters believe Phoenix is on course to become the first major US city to reach an average monthly temperature above 100 degrees. As of July 15, the Maricopa County Department of Public Health (MCDPH) in Arizona has confirmed 18 heat-related casualties so far this summer, with 69 possible heat-related cases currently under investigation.

An infographic heat map provided by the National Integrated Heat Health Information System showing the current temperatures across the United States.

Current Temperature Map: National Integrated Heat Health Information System (NIIHHIS)

Meanwhile, the city of Miami, Florida, recorded its 44th straight day of temperatures exceeding 100 degrees on July 24, of which 26 days observed daily heat index records. In the Southeast, the continuing heat is largely tied to the historic sea surface temperatures in the Atlantic Ocean and Gulf of Mexico that have reached the highest levels on record this month. The marine heat fuels increased humidity in the air, amplifying a region’s surrounding heat index. According to NOAA officials, the elevated water temperatures are also prompting one of the most severe coral bleaching events in Florida’s history.


Federal forecasters have confirmed that last month was the earth’s hottest June ever recorded, breaking a 174-year global climate record. As the recent string of record-breaking temperatures has continued, climate experts anticipate July to reach similar heights and potentially become the “warmest absolute month on record.”

According to the University of Maine’s Climate Reanalyzer, temperatures have only continued to rise throughout July, with the global average temperature in 22 of the first 24 days of the month being hotter than any other single day ever recorded. On July 6, the record was broken for the hottest day in recorded history – a global average temperature of 62.744 degrees Fahrenheit. Additionally, an extreme marine heatwave is pushing sea surface temperatures to approach the highest levels ever recorded; further, Antarctic sea-ice coverage has been observed at record-low levels this month.

Recently, there has been growing urgency internationally to implement improved mitigation and protective measures for extreme weather like heat waves and tropical storms, which have continued to increase in frequency. A report by the Economic and Social Commission for Asia and the Pacific (ESCAP) indicates that nearly $145 billion is needed to develop warning systems and other tools to minimize fatalities and damage from impending disasters. The commission noted that most countries have failed to allocate even 10 percent of the necessary resources. Further, the report warned that China, India, and Japan are at risk of incurring the greatest absolute monetary losses, while it is expected the economies of smaller countries like Vanuatu, Tonga, Palau, and Micronesia would experience even greater damage.

In the US, local and state agencies can receive federal support for extreme heat through the Federal Emergency Management Agency’s (FEMA) mitigation funding opportunities, including the Building Resilient Infrastructure and Communities (BRIC) program, which helps communities increase resilience to various natural disasters. While extreme heat is not among the named natural hazards historically qualified to receive a disaster declaration, many state and local officials are currently urging for its eligibility, as excessive heat has become the number-one cause of weather-related casualties in the country.

When Temps Rise Outside, Get Inside: Ready.gov

According to FEMA, in most of the US, extreme heat is a period of at least two to three days of high humidity and temperatures exceeding 90 degrees; and cautions that excessive heat is often the leading cause of death annually amongst weather-related emergencies. Therefore, FEMA urges individuals living in areas impacted by extreme heat to take necessary safety measures in preparation for and during heat waves. If your community is under an Excessive Heat Warning or Watch, here are some FEMA recommendations for how to keep safe:

  • Seek shelter in an indoor, air-conditioned space;
  • Avoid strenuous activities, especially outdoors;
  • Wear light clothing and stay hydrated;
  • Pay attention to signs of heat-related illness;
  • Never leave people or pets in a closed car; and
  • Make sure your family, friends, and neighbors are staying safe.

To stay informed about extreme heat warnings, NOAA National Weather Service (NWS) provides active alerts in your area. Additional ways to stay updated are through real-time notifications available via the FEMA Mobile App, enabling Wireless Emergency Alerts (WEA) on your phone, NOAA Weather Radio broadcasts, and signing up to receive alerts from your local emergency management office.