Core update impact is measured against a baseline: your traffic in the weeks before the rollout, and the same weeks in earlier years. Search Console deletes both after 16 months. For last spring's update you can still check. For the one that started a two-year slide, the "before" is already gone.
Month17 keeps that baseline and lines every confirmed core update since 2022 up against your clicks, from inside Claude or Cursor.
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A drop on the rollout date proves little
A core update usually takes two weeks or more to roll out, and traffic moves for other reasons in the same weeks. Seasonality, a competitor's new page or a decline that began months earlier can all line up with the date. Blaming the update takes two checks:
- The drop starts during the rollout, measured against the weeks just before it.
- The drop is bigger than the usual swing for that time of year, measured against earlier years.
The first check needs the weeks before the update and the second needs whole years. For any update older than a year, Search Console has neither.
The oldest update is often the one that matters
Updates stack. A page can lose a little in one update, more in the next, and never recover in between. Diagnosing that slide means going back to the first update in it, which is usually the one Search Console deleted first.
How Month17 measures each update
Month17 archives your Search Console data daily and keeps it with no time limit. Its MCP server has a core_update_impact tool that works through Google's confirmed core updates and compares your clicks and average position before each rollout with the weeks after it.
Claude or Cursor can run the second check in the same conversation. Seasonal patterns show whether those weeks dipped in earlier years too, and content decay shows whether the pages were already sliding before the rollout began.
The baseline for the next update starts now
An archive covers the updates it was running for, plus whatever Search Console still held on the day you connected. Connect today and every update from the last 16 months is in range, along with every update after. Once Google confirms the next one, the weeks before it are already saved. The August 2026 spam update post walks through the questions worth asking once a rollout ends.