A CAC that rises during CyberMonday week and a CAC that rises during an ordinary week in March don't mean the same thing, even if the final number is identical. Correctly interpreting seasonality, instead of reacting as if every fluctuation were an account problem, is what separates a brand that plans around the commercial calendar from one that just endures it.
Two types of seasonality, two different responses
Not all seasonality behaves the same way, and confusing the two leads to the opposite of the right decisions:
| Type | What happens | Example | What to do |
|---|---|---|---|
| Demand seasonality | The number of people who want to buy changes, regardless of how you advertise | Mother's Day, back to school | Adjust budget and volume expectations in the same direction as demand |
| Cost (competitive) seasonality | More advertisers compete for the same audience at the same time, raising CPM even though demand for your category doesn't change much | Black Friday, CyberMonday | Budget for a higher CPM in advance; don't mistake a tighter ROAS for a campaign that got worse |
On dates like CyberMonday, both happen at once: real demand rises, but the number of brands advertising rises even faster, which is why ROAS on a date like that can look tighter than in a normal month, without that meaning the date was bad for the business.
The commercial calendar worth having planned (Argentina/LATAM)
| Period | Date(s) | Dominant type |
|---|---|---|
| Summer / sales | January February | Low demand in non seasonal categories; high in summer apparel and travel |
| Back to school | February March | High demand in school supplies, school apparel, technology |
| Hot Sale | May | Both demand and cost high simultaneously |
| Children's Day | August | High demand in toys, children's apparel, entertainment |
| CyberMonday / Black Friday | October November | Very high cost (all categories compete at once); high demand but spread across many brands |
| Christmas / year end | December | Very high demand, high cost, short decision window |
This list is a general starting point, the calendar relevant to each business depends on its specific category. What matters isn't memorizing dates, it's having your own calendar built ahead of time, not discovering it the week it starts.
Planning framework by phase
- Pre season (testing): test creatives and offers on a limited budget before the peak, so you arrive at the date with angles already validated instead of improvising at the moment of highest cost.
- Ramp up: raise budget gradually in the days before, not all at once on the day of the event, this gives each platform's algorithm time to adapt to the new volume (see how much to invest in digital advertising).
- Peak: maximum budget, daily (not weekly) measurement, and room to react quickly to creatives that fatigue faster than usual due to higher exposure frequency.
- Post season: remarket to people who showed interest but didn't close during the peak, and analyze the period against the same event from the previous year, not against just any month.
How to read your metrics during a commercial date
Two adjustments prevent drawing the wrong conclusions:
- Compare against the same period last year, not the immediately preceding month, seasonality means that's the only comparison that isolates the effect of the date.
- Recalculate your breakeven ROAS if the date includes discounts: a tighter margin from the promotion changes the minimum viable ROAS, and comparing it against the ROAS of a month without discounts triggers a false alarm.
Common mistakes
Pausing everything during the low season without leaving remarketing active. Shutting down completely leaves people who already showed interest unattended, as noted in performance marketing for ecommerce, this also hurts repeat purchases.
Raising budget all at once on the day of the event. This doesn't give the platform time to adapt, and usually produces a period of unstable results right when stability matters most.
Comparing the ROAS of a high competition date against a normal month. It's the most common way to wrongly conclude that "the date didn't work."
Frequently Asked Questions
Why does ad cost rise on dates like CyberMonday if my category doesn't have that much extra demand?
Because cost also depends on how many other advertisers are competing for the same audience at the same time, not only on demand for your specific category. It's cost seasonality, not demand seasonality.
Should I pause campaigns during the low season?
Generally, no. It usually performs better to lower the budget and keep remarketing active, rather than cutting all spending and losing contact with people who already showed interest.
How do I know if my campaign actually got worse or if it's just the date?
By comparing against the same period last year and recalculating breakeven ROAS if there were discounts. Without that adjustment, a high competition date will always look worse than it really was.
Conclusion
Seasonality isn't noise to ignore, nor an excuse to explain away any result, it's a plannable variable. Telling whether what's happening is demand or cost, and having the calendar built in advance, is what turns every commercial date into an opportunity instead of a surprise.
Want to walk into the next commercial date with a plan in place? Book a free audit with KLIV and let's plan budget, creative, and calendar together. Book a call →