You can really see the impacts of the enhanced sulfur regulations, coupled with continued warming trends. In the last 15 years, 6 years were hotter than any summer in the preceding 25 years. Only one (2014) was cooler than the median summer for that 25-year timeframe. In fact, every year since 2010, except for 2014, was hotter than at least 17 of 25 summers in the 1985-2009 period. 2025 will almost certainly finish hotter than any summer in 1985-2009, so that would be 7 of 16 years where that was the case. 2 other years (2016 & 2018) were hotter than every summer in the 1985-2009 period, except for 2006.
CONUS Summer rankings of each year since 2010, versus the 25-year period 1985-2009
2010: 4th hottest of 25 (behind 1988, 2002, and 2006)
2011: Hotter than any summer for 1985-2009 period
2012: Hotter than any summer for 1985-2009 period
2013: 9th hottest of 25 (behind 1988, 2002, 2006, 2007, 2003, 2001, 2005 and 1998)
2014: 8th coldest of 25 (behind 1992, 2004, 1993, 2009, 1985, 1997 and 1989)
2015: 5th hottest of 25 (behind 1988, 2002, 2006 and 2007)
2016: 2nd hottest of 25 (behind 2006)
2017: 6th hottest of 25 (behind 1988, 2002, 2006, 2007, and 2003)
2018: 2nd hottest of 25 (behind 2006)
2019: 9th hottest of 25 (behind 1988, 2002, 2006, 2007, 2003, 2001, 2005 and 1998)
2020: Hotter than any summer for 1985-2009 period
2021: Hotter than any summer for 1985-2009 period
2022: Hotter than any summer for 1985-2009 period
2023: 5th hottest of 25 (behind 1988, 2002, 2006 and 2007)
2024: Hotter than any summer for 1985-2009 period