Impact factor is a popular metric used to rank journals in the Web of Science database. It is calculated based on the number of citations received by a journal’s articles in the two previous years, divided by the total number of articles published in those two years.
The impact factor is updated annually, at the end of June. This means that the impact factor and quartile of a journal are only complete up to this point in time.
Clarivate Analytics, the company that produces the Web of Science database, also updates its products in June. This includes the Journal Citation Reports, which provides more detailed information about journal impact factors.
It is important to note that Impact factor is only updated once per year. However, a journal can be discontinued from the Web of Science database in several updates throughout the year.