Seasonality Adjustments

Seasonality Adjustments are a tool that warns Smart Bidding a short-term jump or drop in conversion rate is coming, so it does not overreact or underreact during the event.

You use this when you know something is about to change that the algorithm cannot see yet. A flash sale is about to go live, a product launch is landing at noon, and for those few days your conversion rate is going to behave nothing like a normal week. You tell Google in advance to expect conversion rate to spike over these dates, and Smart Bidding bids into that spike instead of being surprised by it and then scrambling to catch up once the numbers have already moved.

It works the other direction too. If you expect conversion rate to fall, say your checkout is partly down or a promotion is ending, you can flag the dip so the system does not keep bidding as if everything were normal. The point is to smooth the handoff around a known event rather than letting the algorithm learn the change the slow, expensive way.

Keep it to what it is for. Google says seasonality adjustments are ideal for short events of roughly one to seven days, and that they do not work well stretched across long periods. This is a scalpel for a sale weekend, not a dial for a gradual seasonal trend. Smart Bidding already handles ordinary seasonality on its own, so reaching for this tool on a long, fuzzy trend just feeds it bad information.

Short, sharp, and known: that is the only event this tool belongs on.