During the summer, each and every year, American radio listening habits shift. In recent memory, this has meant that stations specializing in music from decades past—in particular, Classic Rock and Classic Hits—see their audience levels rise during the warmest months of the year. The release of Nielsen’s July portable people meter (PPM) results are bringing into focus the 2018 race for “format of the summer,” which is an annual accounting of how radio format audiences change during June, July and August compared with the first five months of the year.

Over the past six years, Pop Contemporary Hit Radio (CHR), Country, Classic Hits and Classic Rock have won this race, with Classic Rock doing so each of the last two years and Classic Hits the two years prior to that. But past history is not a guaranteed measure of future success when it comes to an annual summertime bump, particularly when you consider how playlists evolve and change on a regular basis among the top music radio formats. Evidence of those shifts are clearly noticeable in the following trend, which tracks July results for the top-10 most-listened-to radio formats among Millennial listeners (aged 18-34).

Pop CHR, Country, Adult Contemporary (AC) and Urban Contemporary are the top formats this July among Millennial listeners, based on share of audience. But look back just four short years and the landscape looked significantly different.

•  Pop CHR since 2014 has seen its share among listeners 18-34 decline by nearly 20% (from 12.4% in July 2014 to 10.3% this year).
Country has rebounded in 2018 but is still down from its peak in 2013 and 2014 (2013 was the summer that Country won the “format of the summer” race).
  AC is enjoying a multi-year run of success both on a global basis and with Millennial audiences; the format’s share among listeners 18-34 has increased 28% since 2014.
  Urban Contemporary has also risen steadily—particularly in the summer—going from the sixth-ranked format among Millennials in July 2014 (5.6% share) to the fourth-ranked this July (6.5% share).

As for Classic Rock and Classic Hits, they arrived at the same result in July (a 4.2% share among Millennial audiences) albeit in two distinctly different ways. Classic Hits had its best July book ever in PPM measurement, both with Millennial listeners and among the broader audience (age 6+), where it registered a 5.7% share. This is ahead of the historical July pace for the format and ahead of where Classic Hits was in both 2014 and 2015, when it finished as the top format of the summer. Classic Rock, on the other hand, dropped back slightly during the month, after seeing audience growth in both May and June. The format dipped back to pre-summer numbers across all three of the demographics we track regularly. Among all listeners 6+, Classic Rock went from 5.2% in June to 4.8% in July; among Millennials 4.5% in June to 4.2% in July; and with 25-to-54 year-olds 5.1% in June to 4.9% in July.

With only the August results still to come in, we can take a look at the four formats that have positioned themselves for the home stretch in the format of the summer race. The analysis for the top format each summer is based on the percent rise in total audience (6+) share, by comparing the average of January-May with the average of June, July, and August.