Phoenix concluded, by far, its hottest summer on record. During June-August 2020, Phoenix had a mean temperature of 96.7°. That smashed the old record of 95.1°, which was set in 2013 and tied in 2015. Table 1: Summer 2020 Average Temperatures Since 2009, every summer has ranked among the 20 warmest summers on record. In addition, 2015, 2016, 2019 and 2020 have ranked among the 10 warmest summers. Table 2: 20 Warmest Summers Monthly Mean Temperatures: June: 92.0° (21st war