From January 1999 there are separate articles about months. For the first few years they seem to be forks of the sections concerned in the year articles. The contents of these sections can better be merged into the month article, after which the month articles can be transcluded in the year articles.
For later years the month articles are more comprehensive, the year articles provide a summary.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).