Summary (tl;dr)

Large swathes of the United States are currently under heat advisories and experiencing unseasonably early and record-breaking heatwaves, prompting concern for public health and safety. Similar extreme heat conditions are also affecting parts of South Asia and Europe.

Essential Background

The current widespread heat follows an unseasonably warm period, with March 2026 confirmed as the hottest March ever recorded across the contiguous U.S.. This early onset of summer-like temperatures has exacerbated drought conditions across approximately 60 percent of the continental United States, particularly in the Intermountain West, Plains, and South.

The Full Story

"Heat advisory" is trending as a significant heatwave blankets over 22 U.S. states, impacting more than 60 million people with temperatures forecast to reach or exceed 90 degrees Fahrenheit, and for 11 million, over 100 degrees Fahrenheit. A transient "heat dome" and weaker jet stream winds are identified as the primary drivers behind this intense, early-season heat.

The heat event began in the Western and Plains states, with cities like Las Vegas, Nevada, and Phoenix, Arizona, already breaking temperature records in early May. The extreme heat has since expanded, with heat advisories now issued for parts of the East Coast, including New Jersey, Pennsylvania, Massachusetts, Rhode Island, and Connecticut, where heat index values are expected to near 100 degrees Fahrenheit. This marks the first heat wave of 2026 for some of these regions. Beyond the U.S., severe heatwave conditions are also being experienced in South Asia, including India and Pakistan, and a dramatic swing to extreme heat is expected across parts of Europe, notably Spain, Portugal, France, and England.

Why It Matters

This early and intense heat is critical because it poses significant health risks, as extreme heat is considered the number one weather-related killer. Many people have not yet acclimated to such high temperatures, increasing the danger of heat-related illnesses like heat cramps, heat exhaustion, and heat stroke. Vulnerable populations, including the elderly, children, pregnant individuals, and those with pre-existing health conditions, are particularly at risk. The National Weather Service and partner agencies are observing Heat Safety Week from May 18-22, 2026, to raise awareness about these dangers and promote preventative measures. Experts attribute the increasing likelihood and intensity of such extreme heat events, especially humid heat, to human-induced climate change, with an El Niño pattern expected to further influence global temperatures later in 2026.

Geographic Location

• Las Vegas, Clark County, Nevada, United States (record-breaking temperatures)
• Phoenix, Maricopa County, Arizona, United States (extreme heat warning, temperatures up to 112°F)
• Fresno, Fresno County, California, United States (triple-digit temperatures expected)
• Bakersfield, Kern County, California, United States (temperatures climbed to 102°F)
• Palm Springs, Riverside County, California, United States (temperatures eyeing 110°F and higher)
• Death Valley, Inyo County, California, United States (temperatures could soar to 117°F)
• Salt Lake City, Salt Lake County, Utah, United States (temperatures reaching 94°F, near record)
• Boise, Ada County, Idaho, United States (temperatures reaching 95°F)
• Wichita, Sedgwick County, Kansas, United States (temperatures reaching 95°F)
• Kansas City, Jackson County, Missouri, United States (temperatures reaching 91°F)
• Philadelphia, Philadelphia County, Pennsylvania, United States (record heat and "feels-like" temperatures near 100°F, under a NEXT Weather Alert)
• Eastern Pennsylvania, United States (Code Orange air quality alert)
• South Central Pennsylvania, United States (Code Orange air quality alert)
• Mercer County, New Jersey, United States (heat advisory issued)
• Camden County, New Jersey, United States (heat advisory issued)
• Gloucester County, New Jersey, United States (heat advisory issued)
• Burlington County, New Jersey, United States (heat advisory issued)
• Trenton, Mercer County, New Jersey, United States (expected to experience worst of heat)
• Camden, Camden County, New Jersey, United States (expected to experience worst of heat)
• Bergen County, New Jersey, United States (heat advisory issued)
• Charlotte, Mecklenburg County, North Carolina, United States (moderate heat advisory)
• Worcester County, Massachusetts, United States (first heat advisory of 2026)
• Middlesex County, Massachusetts, United States (first heat advisory of 2026)
• Suffolk County, Massachusetts, United States (first heat advisory of 2026)
• Franklin County, Massachusetts, United States (first heat advisory of 2026)
• Bristol County, Massachusetts, United States (first heat advisory of 2026)
• Essex County, Massachusetts, United States (first heat advisory of 2026)
• Hampshire County, Massachusetts, United States (first heat advisory of 2026)
• Hampden County, Massachusetts, United States (first heat advisory of 2026)
• Norfolk County, Massachusetts, United States (first heat advisory of 2026)
• Plymouth County, Massachusetts, United States (first heat advisory of 2026)
• Rhode Island, United States (first heat advisory of 2026 for parts of the state)
• Connecticut, United States (first heat advisory of 2026 for parts of the state)
• Baltimore, Independent City, Maryland, United States (official start of Code Red Extreme Heat season)
• India (experiencing severe heatwave conditions)
• Pakistan (experiencing severe heatwave conditions)
• Spain (temperatures climbing to mid- to high-30s Celsius)
• Portugal (temperatures climbing to mid- to high-30s Celsius)
• France (temperatures could climb 15°C higher than previous week)
• England, United Kingdom (temperatures could climb 15°C higher than previous week)