The Real Story Behind September’s Search Console Impression Drop

Something unusual happened in mid-September. SEO professionals began noticing strange patterns in Google Search Console. Impressions dropped, average positions shifted, and the number of reported queries changed overnight.

The culprit wasn’t an algorithm update. It was a reporting change that actually improves our understanding of real search visibility.

What Actually Happened

Let me explain what went down. Google quietly stopped supporting something called the &num=100 parameter. This was basically a way that tools and crawlers could pull up to 100 search results per query. When Google cut support for this, all those extra data points just vanished. And with them went a lot of the impressions and position averages we’d been tracking.

Here’s the thing though: the actual search results didn’t change at all. What changed was how Google Search Console reports the data. Third-party platforms lost their ability to see anything beyond positions 1 through 20, and GSC recalibrated to show us real user activity instead of all that automated crawler noise.

Why This Actually Makes Sense

After talking with other SEOs and looking at multiple sites, I realized we really need to rethink how we look at impressions. The data you’re seeing now? That’s your new normal.

Dropping support for the &num=100 parameter honestly makes a lot of sense. I actually saw the same principle play out at my community garage sale last weekend. Fewer choices led to better results.

Plus, it’s just easier for Google to show 10 or 20 results per search than to generate 100 every time. Sure, this shift messed up some tools that were built on that now-unsupported parameter, but it didn’t affect real users at all. What it did do was catch the attention of everyone who monitors every little fluctuation in Google’s reporting.

We didn’t see any visible changes in the actual search results, but Search Console told a completely different story:

• Impressions dropped
• Average position changed
• The number of queries ranking in positions 1 through 20 increased

These shifts really changed how we need to think about GSC data.

The Alligator Effect

Here’s something wild that happened earlier in the year. We noticed this pattern we started calling the “alligator effect.” Starting around February, GSC charts showed impressions rising while clicks stayed steady. It created this shape that literally looked like an open alligator’s mouth.

A lot of people assumed this growth was tied to AI Overviews and an increase in zero-click searches. But when Google ended support for the &num=100 parameter on September 12, that alligator finally closed its mouth.

Turns out, experts now believe automated crawlers were inflating those impression counts. The drop after the change reflects a more accurate baseline, which completely changes how we should interpret impressions going forward.

Here’s something interesting to consider: some of those impressions might have even reflected exposure in large language models like ChatGPT that used third-party tools to scrape Google results. While we can’t confirm this, it suggests those inflated impressions were signals of visibility, just not on Google’s actual search results.

What This Means for Your Reporting

Despite all these fluctuations, GSC is still the most reliable source for keyword ranking data. Especially now that third-party tools can’t capture results beyond positions 1 through 20.

For most reporting situations, you’ll want to annotate the measurement change in GSC and use the current impression and average position levels as your new baseline.

Here’s what I’d suggest adding as an annotation:

“The data reported in Google Search Console (GSC) from 9/13/2025 onwards is the most accurate accounting of how your brand appears in Google organic search. GSC stopped supporting the &num=100 parameter around 9/12/2025 resulting in impressions generated by third-parties and automated crawlers being removed from reporting.”

Now, if you’re using impressions or average position in broader models or long-term trend analyses, you might need to make some adjustments for the period between February 1 and September 12, 2025.

The Simple Method

Use your prior-year impressions and average position up to when things got volatile in early February. For that period when impressions started rising sharply (February 1 through September 12, 2025), revert to prior-year values. Then use GSC data as reported from September 13 onward.

The Advanced Method

You can rebuild historical impressions and average position using trend data and adjustment factors. Take a look at:

• Differences in fluctuation by query type or ranking position (branded vs. non-branded vs. long-tail)
• Metrics like GSC clicks, which weren’t as correlated with impressions during the affected period
• Other factors that weren’t affected by impression volatility

What to Expect Going Forward

Treat these post-change figures as your new baseline. The numbers you’re seeing now reflect how GSC will report visibility from here on out.

Here’s what you can expect:

• Impressions will stabilize at lower levels compared to earlier 2025 trends
• Average position will level out, since it’s calculated relative to impressions
• The number of unique queries reported in positions 1 through 20 will hold steady (with less long-tail data, GSC will show more queries ranking in those positions)
• Clicks and traffic should remain consistent, which confirms that user engagement with your listings hasn’t actually changed

Why These Metrics Still Matter

Even with this recalibration, impressions and average position are still really important indicators of visibility and progress. They’re just measured more accurately now than before.

Consistency: GSC metrics now reflect actual search activity instead of automated crawler data, making them way more reliable for SEO measurement.

Visibility tracking: Still super useful for identifying when your optimizations start to take effect.

Stability: Data for keywords ranking in the top 20 positions shows steadier trends than long-tail terms, since positions beyond 20 aren’t captured anymore.

Moving Forward with Confidence

The impression and average position levels you’re seeing now in GSC represent a much more accurate view of real user search activity. This is your baseline for reporting going forward.

If you’re using impressions or average position in models or performance controls, you can use normalization methods to adjust historical data. But honestly, in most cases, it’s best to just move forward with current figures as they are.

At the end of the day, Google simply made fewer results available. Searchers are still finding what they’re looking for, and third-party tools will adapt. You’ve got a clearer, more honest picture of your search visibility now. That’s actually a good thing.