The June 2021 core update ran from 2 to 12 June 2021, taking 10 days. Google did something it had never done before and has not done since: it announced in advance that this update was incomplete, and that a second part would follow in July. Some sites saw a change in June, saw nothing in July, and some saw the reverse.
An update Google admitted was unfinished
Google stated that some planned improvements were not ready for June and would ship in the July update instead. That is an unusual admission and it had a practical consequence: rankings that moved in June were not the final position, and Google said so at the time.
Sites that dropped in June and reacted immediately were reacting to an interim state. Some of those declines partly reversed in July without anyone doing anything, and some deepened.
Why this matters beyond 2021
It is the clearest evidence available for a rule that applies to every rollout since: do not measure or act until the update completes. Here the completion was five weeks after the start, spanning two separately announced releases.
| Update | Dates | Measurement (what it was) |
|---|---|---|
| June 2021 core update | 2 to 12 Jun 2021 | Part one, explicitly incomplete |
| June 2021 spam update | 23 to 29 Jun 2021 | Unrelated, ran in between |
| July 2021 core update | 1 to 12 Jul 2021 | Part two, completing the change |
Diagnosing a mid-2021 drop
- Treat June and July 2021 as one period. Two halves of one core update with a spam update in the middle.
- Use 1 June 2021 as the boundary. The last clean baseline is the four weeks before that.
- Ignore any measurement taken between 12 June and 12 July. Google said the state was interim, and it was.
Reacted to a drop that then partly reversed?
Acting mid-rollout is the most common expensive mistake in this work, and it makes the result impossible to attribute afterwards. Send your Search Console access and I will read it properly.
Get free recovery auditSource: Google ranking updates list
Traffic dropped around Jun 2, 2021?
Get a free preliminary diagnosis. I confirm whether this core update is the cause before you spend on fixes.