Google Ads Seasonality Adjustments: Plan for Sales Spikes

1. What Google Ads Seasonality Adjustments Actually Do

Quick Answer: A seasonality adjustment is a scheduled conversion rate change you hand to Smart Bidding before an event. You give it a start date, an end date, and a percentage — “expect conversions to come 40% easier for these three days”. Google bids more aggressively during the window, then returns to normal by itself.

Smart Bidding decides each bid partly on how likely a click is to convert. When you know that likelihood is about to jump, because the price drops 30% on Friday, you can say so in advance instead of waiting for the system to work it out from live data.

Three details from Google’s About seasonality adjustments documentation decide almost everything else:

• It is a conversion rate lever, not a traffic lever. More searches during Raya is not a reason to use it. A higher rate of buying among the people who click is.
• It expires on its own. Campaigns return to pre-adjustment behaviour when the window closes. You never need to enter a negative adjustment afterwards to cancel it out.
• It is for major changes only. Google’s guidance is explicit that Smart Bidding already manages ordinary seasonal movement. The tool exists for the ones it cannot see coming.

This is also what separates it from the older device, time and location bid adjustments. Those set a percentage on your bid and are mostly ignored by Smart Bidding. A seasonality adjustment sets a percentage on the predicted conversion rate, and Smart Bidding is the only thing that reads it.

2. Which Campaigns Can Even Use One

Quick Answer: Search, Standard Shopping and Display campaigns qualify only on Target CPA or Target ROAS. Performance Max and App campaigns qualify on any bid strategy. Travel campaigns are not supported. If your Search campaign runs Maximize clicks or manual CPC, the setting will not apply to it.

Eligibility per Google’s Create a seasonality adjustment documentation.

Scope is the part people get wrong. You can apply an adjustment to a campaign type, to specific campaigns, or across a manager account, with a limit of 2,000 campaigns per event. This is where how you organise your campaigns pays off: an account split by product line lets you adjust only the range that is actually on promotion.

3. Malaysia’s Conversion Rate Calendar, Month by Month

Quick Answer: Across ZenWeb-managed accounts, Malaysia’s big calendar moments split into two kinds. Raya, Chinese New Year and Merdeka move search volume but barely move conversion rate. The 11.11 and 12.12 sale days move conversion rate sharply. Only the second kind is a seasonality adjustment case.

Malaysia is close to fully online. DataReportal’s Digital 2026: Malaysia report counts 35.4 million internet users at 98.0% of the population, so the festive calendar lands in your account whether you plan for it or not. What it does to conversion rate is a separate question from what it does to traffic.

Read the last two columns together and the pattern is hard to miss. Raya moves people to search. The sale days move people to buy. A festive week where traffic climbs and the buying rate holds steady needs money in the campaign, which is a monthly budget decision rather than a bidding one.

Raya week itself is the quiet one. Everyone is balik kampung, the office is shut, and conversion rate falls through the floor. That is a legitimate negative adjustment, and almost nobody sets it. If your leads arrive by phone, it is also the week to check whether the calls your ads generate are being answered at all.

4. How Big Is the Lift? It Depends on the Offer

Quick Answer: A deep sitewide discount moves conversion rate hardest — a 25% or better price cut lifts it by around half again across ZenWeb accounts. A free-gift or bundle promo barely moves it. A festive campaign with no offer attached moves it not at all. The size of your adjustment should follow the offer, not the occasion.

The number you type in the box forecasts your own conversion rate. The useful question is therefore not how big Raya is, but how big your offer is during Raya.

The bottom row is the one worth sitting with. A festive banner and a Raya-themed headline lift conversion rate by roughly nothing. Advertisers still set a +40% adjustment for that campaign every year, then wonder why April’s CPA looks so ugly.

Two things genuinely raise the buying rate, and neither is the artwork: a real price cut, and a landing page that carries it. If the ad promises 30% off and the click lands on the usual homepage, the lift never arrives, which is why the offer belongs in the form or lead capture itself.

5. Why Long Adjustments Backfire

Quick Answer: Google recommends seasonality adjustments for events of 1–7 days and warns they may not work well beyond 14. ZenWeb account data agrees: short windows land close to target, while month-long adjustments overshoot during the event and leave a raised CPA behind for a fortnight afterwards.

The reason is straightforward. Over a long window, Smart Bidding has time to learn the real conversion rate from live data, while your adjustment keeps shouting a forecast over the top of it. The system ends up bidding against a number that stopped being true in week one.

The last column is the one that costs money. A 15-day adjustment leaves the bid strategy re-learning for a fortnight afterwards at a CPA well above where it started. You end up paying for the promo twice.

If your promotion runs for a month, it is not a seasonality adjustment case at all. It is a budget and target decision, and it deserves a proper test rather than a guess, which is what Google Ads experiments exist for.

6. The Cost of Guessing Too High

Quick Answer: Over-stating the lift is worse than under-stating it. Tell Google to expect +60% when the true lift is +20%, and it bids as if every click is far more valuable than it is — you buy expensive clicks that convert at the ordinary rate. Under-stating simply leaves some volume on the table.

The table below is an illustrative model, not measured results. It assumes a RM 5,000 promo budget, a 3% baseline conversion rate and a RM 90 target CPA, then applies the basic rule that bids scale with predicted conversion rate.

Notice how gentle the penalty is above the accurate row and how steep it is below. Guessing low costs a handful of conversions. Guessing high costs a third of them. When in doubt, round down.

The forecast also has to rest on something real. If your account treats every form fill and every WhatsApp tap as the same conversion, you cannot know your true rate, which is why setting proper conversion values comes first. And if the lift is really just past customers returning for the sale, Customer Match handles that audience better than any bid forecast.

7. How to Set a Seasonality Adjustment

Quick Answer: In Google Ads, go to Tools, open Budgets and bidding, click Adjustments, and choose the Seasonal tab. Add a conversion rate adjustment, name it, set the exact start and end dates, choose the campaigns it applies to, and enter your expected conversion rate change. Set it before the event, not during.

1. Check you can get in. Settle Google Ads account ownership and access long before the promo week.
2. Confirm the bid strategy. Target CPA or Target ROAS on Search, Shopping and Display; any strategy on Performance Max. Anything else and the adjustment will not apply.
3. Open the Seasonal tab. Tools → Budgets and bidding → Adjustments → Seasonal, then the blue plus button, then Conversion rate as the adjustment type.
4. Set the exact window. Dates matching the offer, not the campaign. If the sale is Friday to Sunday, the adjustment is Friday to Sunday.
5. Scope it to the promoted campaigns only. Choose specific campaigns rather than all campaign types, unless the whole account really is on sale.
6. Enter your forecast conversion rate change. Base it on the same promotion last year. With no history, use a modest number and review afterwards.
7. Save it a few days early, then leave it alone. Every mid-flight edit restarts the guesswork.

One thing you never need to do is cancel it. Google’s documentation is clear that campaigns return to pre-adjustment behaviour once the window closes.

8. Seasonality Adjustments vs Data Exclusions vs Budget

Quick Answer: Three different tools sit in the same menu. A seasonality adjustment forecasts a real conversion rate change. A data exclusion tells Smart Bidding to ignore a period when tracking broke. A budget change handles more demand. Picking the wrong one is the most common festive mistake in Malaysian accounts.

Data exclusions are the ones people misuse most. They exist for tracking outages, such as a tag that fell off or a site that went down, and Google warns against using them frequently or removing them once applied. They repair broken data; they do not run promotions. If you reach for one every festive season, the real problem is usually conversion tracking that was never set up properly.

Two more checks before a big sale week. If the surge comes from places you do not sell to, tighten location targeting first, because no conversion rate forecast saves you from the wrong audience. If the extra volume arrives through Google Search Partners rather than Google itself, check how it converts before you bid it up. And for festive awareness reach, a Demand Gen campaign is a better home for the budget than a bid forecast on Search.

9. Conclusion: Forecast the Buying Rate, Not the Occasion

Quick Answer: Google Ads seasonality adjustments are a precise tool for a narrow job — a short, sharp change in how often clicks turn into customers. Used on a 3-day sale with a real discount, they earn their place. Used on a month-long festive campaign with a themed banner, they cost you money twice.

Most Malaysian festive planning does not need this setting at all. It needs a budget that survives the weekend, a landing page that carries the offer, and someone in the office to answer the phone. Where the tool does belong, on 11.11, a flash sale, or the dead week after Raya, set it short, honest and early.

If you would rather have the calendar mapped before the quarter starts, that is what ZenWeb’s Google Ads team does for 500+ Malaysian businesses.

10. Frequently Asked Questions

1. How long should a Google Ads seasonality adjustment run?

Google recommends 1–7 days and warns that adjustments may not work well beyond 14. ZenWeb account data agrees: windows of 1–3 days land close to target CPA, while windows of 15 days or more overshoot and leave CPA raised for roughly a fortnight afterwards.

2. Do I need to remove the adjustment after the sale ends?

No. Google’s documentation states that campaigns return to their pre-adjustment performance once the window closes. The only reason to set a negative adjustment is a genuine expected drop, such as the week your office is closed for Raya.

3. Which campaigns support seasonality adjustments?

Search, Standard Shopping and Display campaigns on Target CPA or Target ROAS, plus Performance Max and App (beta) campaigns on any bid strategy. Travel campaigns are not supported. A Search campaign on manual CPC or Maximize clicks ignores the adjustment entirely.

4. Should I use one for Hari Raya or Chinese New Year?

Usually not for the festive period itself. Across ZenWeb-managed accounts, those weeks lift search demand far more than conversion rate, which makes them a budget decision. The exceptions are the final week before Raya with a real discount running, and Raya week itself, where a negative adjustment often fits.

5. What number should I enter if I have no history?

A conservative one. Over-stating the lift costs far more than under-stating it: bids scale up while the real conversion rate stays flat, so you buy costlier clicks at the ordinary rate. Set a modest figure, measure what the promotion actually did, and use that number next year.