Major US cities experience hotter temperatures than surrounding areas due to the urban heat island effect.

• This effect is caused by factors like buildings, pavement, and lack of trees.
• An analysis by Climate Central found 34 million people in 65 cities face temperatures 8 degrees Fahrenheit higher than nearby areas.
• New York City has the strongest heat island effect, with temperatures potentially 9 degrees Fahrenheit hotter than surroundings.
• Other populous cities like Chicago, Philadelphia, Houston, San Diego, Dallas, and Los Angeles also experience significant heat amplification.

Read more at The Guardian website.