Phoenix breaks record with 19th straight day of 110-degree highs

Phoenix's summer has officially gone from abnormally hot to record-breaking as the temperature at Sky Harbor International Airport hit 110°F for the 19th consecutive day, the longest streak ever recorded in the Valley.

Driving the news: The National Weather Service recorded temperatures of 110 at the airport Tuesday.

• The previous record of 18 straight days of 110-plus highs was initially set in 1974, which was tied Monday with a high temperature of 116.
• 110-plus highs are expected to continue throughout the week, meaning each day is likely to set a new record.
• The same is true for our streak of excessively high overnight lows. Phoenix set a new record for consecutive days with lows of at least 90°F Monday, and set a new mark this morning with its 9th straight day when the mercury bottomed out at 94°F.

The big picture: The southwestern and southern U.S. are grappling with a "relentless" heat wave that left 104 million Americans under extreme heat alerts Tuesday, Axios' Andrew Freedman reports.

• The triple-digit highs, along with excessive nighttime lows that make it difficult for peoples' bodies to cool down after arduously hot days, pose significant health risks.
• The elderly, young, those with chronic illnesses and unhoused people are at especially high risk for heat-related illness, but even healthy individuals can quickly succumb to such high temperatures.

Context: Heat waves are becoming more intense, longer-lasting and more frequent due to human-caused climate change.

Zoom out: The U.S. isn't alone. Europe, the Middle East and China are also coping with extreme heat this summer.