How to Use Seasonality Adjustments in Google Ads for Better Year-Round Performance
Digital advertising is never “flat.” Some weeks, people buy faster; some weeks, they browse and delay. If you use Smart Bidding (Target CPA, Target ROAS, and certain other automated strategies), Google’s system learns from historical conversion data and tries to predict what each click is worth.
That works well most of the time. The trouble starts when you already know a short, unusual event is about to change conversion behaviour, like a 48-hour sale, a product restock, or a holiday dip. In those moments, seasonality adjustments can help you steer the algorithm so it reacts immediately, without learning the wrong lesson from a temporary spike or slump.
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What are seasonality adjustments in Google Ads?
A seasonality adjustment is an advanced control that lets you schedule an expected conversion rate change (up or down) for a specific time window. You are basically telling Google: “During this period, conversion rates will be different from normal, and it is temporary.”
Important detail: the percentage you enter is a change relative to your baseline, not the final conversion rate. For example, “+50%” means “my conversion rate will be 50% higher than normal during this event.”
Why seasonality adjustments matter
Smart Bidding is data-driven. If conversion rates suddenly jump or drop, the system may either:
- Underbid during the best window because it has not adapted yet, or
- Overcorrect after the event, because it assumes the temporary change is the new normal.
Seasonality adjustments are designed to reduce that risk by helping your bidding strategy stay stable through short volatility.
When you should use them
Google recommends seasonality adjustments for short events, typically 1 to 7 days, and only when you expect a major conversion rate change. They may not work as well when used for longer stretches, especially more than 14 days.
Common good use cases:
- Flash sales and limited-time promotions (24 to 72 hours)
- Black Friday or similar high-intent shopping windows
- Product launches or restocks that you know will boost purchase intent
- Short predictable slowdowns (for some B2B accounts, holiday week dips can be very real)
When you should NOT use them
Seasonality adjustments are not meant for slow, long seasonal patterns (like “Q4 is always better for retail”). Smart Bidding is already built to handle gradual changes over time, so frequent adjustments can confuse performance.
Also note: seasonality adjustments are not supported for Travel campaigns.
If your issue is a tracking outage or broken conversion data, you should not “fake it” with seasonality. Use the correct fix (like data exclusions or repair tracking) instead of telling the algorithm a made-up conversion shift.
Which campaigns can use seasonality adjustments?
Per Google’s documentation, seasonality adjustments are available for:
- Search, Standard Shopping, and Display campaigns using Target ROAS or Target CPA
- Performance Max campaigns
- App campaigns (beta) using all bid strategies
- And they are not supported for Travel campaigns.
How to set up a seasonality adjustment (step by step)
Inside Google Ads:
- Click the Tools icon
- Go to Budgets and bidding
- Click Adjustments
- Choose Seasonal
- Click the plus button to create a new adjustment
- Select Conversion rate as the adjustment type
- Name it (example: “Weekend Sale Feb 2026”) and optionally add notes
- Set the start and end date and time (hour level)
- Choose the scope (all campaign types, specific campaign types, specific campaigns, and for App campaigns only, specific ad groups)
- Enter the expected conversion rate change percentage (positive or negative)
- Save and create the adjustment
After the event ends, campaigns return to their prior behaviour automatically, so you do not need to add a “negative” adjustment to undo it.
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How to pick the right percentage (the part most people guess)
A practical way to estimate your adjustment:
- Look at the most similar event last year (or last time you ran the promo).
- Compare the conversion rate during the event vs the two to four weeks before it.
- Convert that into a relative change.
Example:
- Normal conversion rate: 2.0%
- Expected event conversion rate: 3.0%
That is a 50% lift (because 3.0 is 1.5× 2.0), so you would set +50%.
For dips, it works the same way:
- Normal conversion rate: 4.0%
- Expected holiday week conversion rate: 3.0% That is a 25% drop, so you would set -25% as your adjustment (a decrease)
If you are not confident, go conservative. Overstating the swing can push bids too hard and create volatility.
Quick best practices that keep results clean
- Keep the window tight. Match the real start and end time, not the whole week “just in case.”
- Use it only for major changes. If the impact is small, let Smart Bidding do its job.
- Scope it correctly. If only one product line is on sale, apply the adjustment only to campaigns that actually change.
- Review after the event. Save a simple note: expected change vs actual change, and what you would do next time.