We all know the rhyme.
Thirty days has September, April June and November.
All the rest have 31, except February which has 28.
This is true everywhere that uses the western or Gregorian calendar. Except in radio.
The A.C. Nielsen service measures radio listening year round and releases monthly ratings results – 13 of them! In other words, only in the world of radio are there 13 months.
How? If every month had 28 days, 364 days would be the equivalent of 13 months. That’s how. Radio measures in four week increments.