Most businesses want December to be calm. For many site owners in 2020 it was anything but. Google released a broad core update on 3 December 2020, just after Black Friday and Cyber Monday and right before the holiday period, and data providers soon described it as one of the bigger core updates they had measured.
Coming roughly seven months after the May 2020 core update, during a year already reshaped by the pandemic, the December 2020 core update is a case study in how timing and scale make analysis harder. Seasonal demand, shifting user behaviour and a large algorithm change all overlapped.
This guide covers the confirmed dates, the volatility pattern reported during the rollout, how it compared with May 2020, why the timing upset many in the industry, and a practical way to separate holiday seasonality from algorithmic change.
Key Takeaways
- Google released the December 2020 Core Update on 3 December 2020 and it completed on 16 December 2020.
- Volatility spikes were reported around 4 December and 10 December.
- Based on data providers' reports, it was even bigger than the May 2020 core update, though Google itself did not rank updates by size.
- The release, right after Black Friday and Cyber Monday but before the holidays, upset many in the industry.
- Holiday seasonality makes December data unusually hard to read, so compare like-for-like periods and segment carefully.
December 2020 core update at a glance
| Item | Detail |
|---|---|
| Name | December 2020 Core Update |
| Start | 3 December 2020 (live around 1pm US Eastern time) |
| End | 16 December 2020 |
| Duration | About two weeks, in line with Google's typical one-to-two-week estimate |
| Type | Broad core update |
| Confirmed by Google? | Yes, announced in advance by Google's Search Liaison |
| Reported volatility spikes | Around 4 and 10 December 2020 |
| Previous core update | May 2020 (4 to 18 May 2020) |
What Google said
Google followed its usual pattern: a short heads-up, the update's name, then confirmation that it was live. It also set expectations about the rollout length.
“it will typically take about one to two weeks to fully roll out.”
— Google Search Liaison, quoted by Search Engine Land, Google December 2020 core update rolling out
Google again provided no specific recovery steps, pointing instead to its existing core update guidance. Search Engine Land's coverage also noted Google had said some recovery can be seen between core updates, a message Google's documentation repeats today alongside the warning that bigger changes usually show at the next core update.
How big was it?
Google does not publish a size ranking for core updates. The "big" label comes from third parties. Search Engine Land's 2020 review said that, based on some reports, the December update was even bigger than May 2020, which itself had been described as larger than January 2020. The same review reported big spikes in volatility on 4 December and 10 December.
Two cautions apply. First, size is measured on each tool's tracked keywords, not your site. Second, a larger update means more sites moved, but says nothing about why any single site moved. Our explainer on how Google rolls out core updates explains why mid-rollout spikes are normal.
| 2020 core update | Dates | How it was described in coverage |
|---|---|---|
| January 2020 | 13 to 16 January | Big and broad; quick rollout |
| May 2020 | 4 to 18 May | Bigger than January; some called it a monster |
| December 2020 | 3 to 16 December | Reportedly even bigger than May |
The holiday timing problem
Search Engine Land wrote that the update was released right after the Black Friday and Cyber Monday shopping season but still before the holidays, which upset many in the industry. For ecommerce and seasonal businesses, a large ranking change during peak weeks is uncomfortable, and it complicates diagnosis afterwards because demand itself shifts sharply through December.
Here is a practical method for separating the two effects:
- Pull Search Console data for 3 to 16 December 2020 and the same dates in 2019, so you compare holiday periods with each other.
- Look at average position and impressions for a stable set of non-seasonal queries; position changes on those are more likely algorithmic.
- For seasonal queries, compare your click share against the change in total impressions; if demand rose but your clicks fell, that points to ranking loss.
- Segment by page type (category, product, blog, guides) to see whether one template moved more than others.
- Wait at least a week after 16 December before drawing conclusions, as Google recommends for core updates.
- Record findings, then check how the same pages behaved in the June and July 2021 core updates.
Our guides on seasonality versus algorithm updates and before-and-after core update comparisons go deeper on both steps.
What to do if you were affected
The core advice did not change in December 2020 and has not changed since. Google's documentation says pages that drop aren't necessarily bad, that you should avoid quick-fix changes, and that meaningful content improvements are the way forward. Practical priorities:
- Review the pages that lost most against the questions in our helpful content guidelines.
- Compare your losing pages with what now ranks to understand shifts in intent or depth.
- Fix genuine technical problems if you find them, but don't expect technical tweaks alone to reverse a core update effect.
- Plan improvements for the long term rather than for the next few weeks.
Lessons that still apply in 2026
Google now announces core updates on the Search Status Dashboard rather than only on social media. The underlying lessons from December 2020 have held up well:
- Large updates can land at commercially awkward times, so keep a written plan for what you will and won't change during a rollout. Our guide on what to do during a core update rollout covers this.
- Third-party volatility scores tell you the weather, not your own result.
- Year-on-year comparisons are essential for any business with seasonal demand.
- Improvements made after an update are judged over time, so patience is part of the strategy.
Common mistakes
- Comparing December with November. Seasonal demand alone can explain large swings.
- Treating tracker volatility as your result. Your Search Console data is the ground truth for your site.
- Making changes during peak trading. Rushed edits in mid-December made later analysis harder.
- Assuming the update targeted ecommerce. Google gave no such indication; it was a broad update.
- Expecting a quick bounce in January. Recovery, if it comes, typically shows over months or with later updates.
Where it fits in the timeline
December 2020 closed a year of three core updates: January, May and December. The next core updates were the two-part June 2021 and July 2021 updates. For context on every update, see our Google algorithm updates history.
Related Guides
- Google Passage Ranking: How Individual Passages Get Ranked
- Google MUM Explained: What It Does (and Doesn't Do) in Search
- Google's June 2021 Core Update: Part One of a Two-Part Update
Frequently Asked Questions
When did the December 2020 core update roll out?
It started on 3 December 2020 and finished on 16 December 2020.
Was the December 2020 core update bigger than May 2020?
Search Engine Land reported that, based on some data providers, it was even bigger than May 2020. Google did not rank its size.
Why was the timing controversial?
It came right after Black Friday and Cyber Monday but before the holidays, which upset many in the industry because of peak-season risk.
How do I tell seasonality from the update?
Compare the same dates year on year, focus on positions for stable non-seasonal queries, and segment by page type.
Did Google give recovery advice?
Google pointed to its existing core update guidance: focus on meaningful content improvements rather than quick fixes.
Conclusion
The December 2020 core update showed how a large, broad update and seasonal demand can blur together. Careful year-on-year comparison and patient, quality-focused improvement remain the best response. If you need help untangling a traffic drop, our ecommerce SEO and SEO services teams can help, or you can get a free quote.
