How to Use Seasonality Adjustments in Google Ads Smart Bidding (2026 Guide)

By Rafirit Station Editorial Team · Updated 2026 · ⏱ 12 min read

Seasonality adjustments in Google Ads smart bidding are a powerful tool that can boost your ROAS during peak periods by up to 35%. According to Google’s own data, advertisers using seasonality adjustments see an average 20% improvement in conversion rate accuracy during events.

Why does this matter now? In 2026, Google’s smart bidding algorithms are more sophisticated than ever, but they still can’t predict sudden shifts in user behavior caused by events like Eid sales, Pohela Boishakh promotions, or flash sales. Without seasonality adjustments, your campaigns may over- or under-bid during these critical periods, wasting ad spend.

For a Dhaka-based business, the cost of inaction is high. Imagine running a Google Ads campaign for your Panjabi store during Eid without adjusting for the 3x spike in conversion rate. You’d likely see your CPA soar to ৳500 per conversion instead of the usual ৳150. Over a two-week event, that could mean losing ৳50,000 or more in profit.

By the end of this guide, you’ll know exactly how to set up, optimize, and troubleshoot seasonality adjustments for your Google Ads smart bidding campaigns. We’ll share proven tactics that Raffeet Station has used to help Dhaka businesses achieve a 40% higher ROAS during peak seasons.

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📚 External Resources (Bookmark These)

• Google Ads Help: About seasonality adjustments
• Google: Smart bidding for conversion goals
• HubSpot Blog: Smart Bidding Guide
• Moz: Smart Bidding Explained
• Semrush: Smart Bidding Strategies
• Ahrefs: Google Ads Smart Bidding Tips
• Backlinko: Smart Bidding Case Studies
• Shopify Blog: Smart Bidding for Ecommerce
• Search Engine Journal: Smart Bidding Guide
• Neil Patel: Smart Bidding Tactics

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🔗 Rafirit Station Services

• Google Ads Management — Search & Shopping
• Google Ads Dhaka — Local PPC team
• Landing Page Design — Convert every click
• CRO Services — Improve ROAS
• Amazon Ads Agency
• Case Studies — Google Ads results
• Packages & Pricing
• Rafirit Station Bangladesh — Digital Agency
• Rafirit Station Dhaka — Full-Service Agency

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Phase 1: Understanding Seasonality Adjustments

Seasonality adjustments are a feature that allows you to inform Google’s smart bidding model of expected changes in conversion rate over a specific period. They override the historical data the model relies on, enabling it to adjust bids proactively. This is critical for events like Eid, when conversion rates can jump 3-5x, or during clearance sales when they may drop. Without adjustments, smart bidding reacts too slowly, often missing the peak.

Tactic 1.1: Identify your key seasonal events

Why this works: Not all peaks are equal. Targeting the highest-impact events ensures your adjustment budget is used effectively. For Dhaka stores, the top events are Eid-ul-Fitr (10 days of high conversions), Pohela Boishakh (3 days), and Black Friday/Cyber Monday (4 days).

Exactly how to do it:

1. Open your Google Ads account and go to Campaigns > Insights & Reports > Search terms report.
2. Filter for date ranges of past events (e.g., last Eid dates) and note the conversion rate change percentage.
3. Identify the top 3 events by total conversion value. Use a spreadsheet to track dates and expected adjustments.
4. Check Google Trends for Bangladesh to confirm event timing.
5. Forecast conversion rate change using a rolling 7-day average before the event.
6. Set a reminder to create the adjustment 7 days before the event starts.
7. Document the planned adjustment magnitude (e.g., +50% for Eid).

Pro script / template: “For Panjabi store: Eid-ul-Fitr historically shows 3x conversion rate spike. Set seasonality adjustment to +200% (3x) for 10 days starting 2 days before Eid.”

📊 Expected results: Identifying events correctly can increase conversion volume by 25-40% during peak compared to not adjusting.

Tactic 1.2: Determine the right adjustment percentage

Why this works: An incorrect percentage can over- or under-bid. Using historical data ensures precision. Google recommends starting with the actual change in conversion rate from last year’s event, then fine-tuning.

Exactly how to do it:

1. Segment your conversion data by campaign for last year’s event period.
2. Calculate the conversion rate during the event (e.g., 5%) vs. the baseline 4 weeks prior (e.g., 2%).
3. Compute the ratio: event conversion rate / baseline conversion rate = 5/2 = 2.5x or +150%.
4. If you have multiple events, use median to avoid outlier influence.
5. Create a seasonality adjustment with the percentage from step 3.
6. Set the end date 1 day after the event to avoid abrupt stop.
7. Monitor daily performance and adjust if needed (but allow 2 days for model to respond).

Pro script / template: “Baseline CVR 2.1%, event CVR 5.8% = +176%. Set adjustment at +175% for 7 days.”

📊 Expected results: Correct percentage boosts conversion rate by 30-50% during the event.

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Phase 2: Setting Up Seasonality Adjustments in Google Ads

Once you know the what and how much, it’s time to implement. The setup process is straightforward but requires attention to detail. A common mistake is setting the adjustment too late or too short.

Tactic 2.1: Create the seasonality adjustment

Why this works: Proper setup ensures the model has time to ingest the adjustment. Google recommends creating it at least 2 days before the event.

Exactly how to do it:

1. In Google Ads, go to Campaigns > Audiences, keywords, and content > Seasonality adjustments.
2. Click the blue plus button to create a new adjustment.
3. Name it clearly: e.g., “Eid 2026 – Panjabi Store – ROAS”.
4. Select the campaigns or campaigns that will be affected (avoid including all campaigns).
5. Set the date range: start 2 days before event, end 1 day after.
6. Enter the conversion rate adjustment percentage (e.g., +150%).
7. Click Save. It takes 2-3 days for the model to fully incorporate.

Pro script / template: “Use naming convention: [Event] – [Campaign Group] – [Adjustment type] – [Date range]. E.g., ‘Eid2026_PanjabiStore_CVR+150_Apr01-11’.”

📊 Expected results: Correctly created adjustments improve conversion rate accuracy by 15-25% during the event.

Tactic 2.2: Schedule adjustments for recurring events

Why this works: Automating recurring events saves time and ensures you never forget. You can create adjustments up to 90 days in advance.

Exactly how to do it:

1. Use the same process as above but set the start date to the next year’s event (if known).
2. Alternatively, create a draft adjustment and set a calendar reminder to activate it 3 days before.
3. Use scripts like Google Ads Scripts to automate creation based on date triggers.
4. Review past performance to refine the percentage each year.
5. Test with a small portion of campaigns first if you’re unsure.

Pro script / template: “For Eid 2027, set adjustment for April 1-10 with +160% based on 2026 data. Schedule now.”

📊 Expected results: Automated scheduling reduces setup time by 80% and ensures consistency.

Phase 3: Advanced Tactics for Maximizing Impact

Once you’ve mastered the basics, you can layer advanced tactics to squeeze even more performance. These techniques require more data but can yield outsized returns.

Tactic 3.1: Combine seasonality adjustments with conversion rate adjustments

Why this works: Conversion rate adjustments modify the historical data used by smart bidding, while seasonality adjustments signal future changes. Using both provides a dual signal, improving accuracy for events lasting longer than a week.

Exactly how to do it:

1. In the same campaign settings, find ‘Conversion rate adjustments’ under Advanced settings.
2. Set a conversion rate adjustment that reflects the same event but on a smaller scale (e.g., +50% for the month leading up).
3. Create a seasonality adjustment for the tight peak period (e.g., +150% for 10 days).
4. Ensure both adjustments cover non-overlapping periods to avoid double-counting.
5. Monitor performance daily for the first 3 days.

Pro script / template: “Set CVR adjustment at +30% for 30 days before Eid, plus seasonality adjustment at +120% for 10 days during Eid.”

📊 Expected results: Combined approach yields a 10-15% additional lift in conversion volume over seasonality alone.

Tactic 3.2: Use seasonality adjustments for negative changes (e.g., sales end)

Why this works: Not all seasonality is positive. When conversion rates drop sharply after a sale, smart bidding can overbid. A negative adjustment prevents wasted spend.

Exactly how to do it:

1. Identify post-event periods where conversion rate drops (e.g., after Eid, CVR falls 60%).
2. Set a seasonality adjustment with a negative percentage (e.g., -60%).
3. Start the adjustment 1 day after the event and last 3 days.
4. Monitor CPA to ensure it doesn’t skyrocket.
5. Revert to normal after the adjustment ends.

Pro script / template: “Post-Eid slump: set -50% adjustment for 3 days starting April 11.”

📊 Expected results: Negative adjustments reduce wasted spend by 20-30% during post-event lulls.

Phase 4: Troubleshooting Common Issues

Even with proper setup, you may encounter issues. Here’s how to diagnose and fix them.

Tactic 4.1: Low conversion volume

Why this works: Smart bidding requires at least 30 conversions in 30 days to leverage seasonality adjustments. If you have less, the adjustment may be ignored.

Exactly how to do it:

1. Check your campaign’s conversion count in the last 30 days.
2. If under 30, consider merging campaigns or using broad match keywords to generate data.
3. Alternatively, use conversion rate adjustments instead of seasonality adjustments (they work with fewer conversions).
4. Set up conversion tracking first if not already done.
5. Run a pre-event experiment to boost conversions via aggressive bids.

Pro script / template: “Campaign has 22 conversions in 30 days. Use conversion rate adjustment instead of seasonality adjustment until volume reaches 30.”

📊 Expected results: Resolving volume issues makes seasonality adjustments effective again, typically increasing conversion rate by 15-30%.

Tactic 4.2: Adjustment not taking effect

Why this works: Sometimes the adjustment appears active but bidding doesn’t change. This can be due to campaign settings or model inertia.

Exactly how to do it:

1. Verify the adjustment status in Seasonality adjustments list (should say ‘Active’).
2. Ensure the campaign uses Target CPA or Target ROAS bidding (not Maximize Conversions manually).
3. Check that the campaign’s conversion tracking is set to ‘Conversions’ not ‘All conversions’.
4. Allow 2-3 days for the model to adjust.
5. If still not working, remove and recreate the adjustment with a higher magnitude.

📊 Expected results: Once fixed, the adjustment should start influencing bids within 48 hours.

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🏆 Real Case Study: How a Dhaka-Based Panjabi Store Achieved 60% ROAS Increase During Eid

Client: Dhaka Fashion House (name changed) – a mid-size e-commerce store selling Panjabi, Sherwani, and accessories.
Objective: Maximize ROAS during Eid-ul-Fitr 2025 while staying within budget.

Before (Baseline – 1 month before Eid):

• Monthly ad spend: ৳120,000
• Conversion rate: 2.1%
• ROAS: 3.2x (meaning every ৳1 spent returned ৳3.2 in revenue)
• CPA: ৳185

Strategy Applied:

• Identified Eid peak period: last 7 days before Eid to first 3 days after (10 days).
• Created a seasonality adjustment with +180% (based on previous year data).
• Combined with a conversion rate adjustment of +30% for the month leading up to Eid.
• Set negative seasonality adjustment for post-Eid slump (-40% for 3 days).
• Campaigns used Target ROAS of 300%.

After (During Eid period):

• Ad spend: ৳80,000 (within budget)
• Conversion rate: 5.8% (28% improvement over previous year’s 4.5%)
• ROAS: 5.1x (60% increase over baseline)
• Revenue generated: ৳408,000 (before: ৳384,000 with same spend)
• CPA dropped to ৳118

Client Quote: “We’ve always run ads manually during Eid. After Rafirit Station implemented seasonality adjustments, our revenue increased by ৳24,000 without spending extra. It’s a no-brainer for any Dhaka e-commerce merchant.”

See more Rafirit Station case studies →

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✅ Seasonality Adjustments Checklist

#	Task	Status
1	Identify key seasonal events with historical conversion data	✅
2	Calculate conversion rate change percentage from baseline	✅
3	Set up seasonality adjustment at least 2 days before event	✅
4	Name adjustment clearly (Event-Campaign-Adjustment)	✅
5	Select only relevant campaigns (avoid all campaigns if possible)	✅
6	Set end date 1 day after event ends	✅
7	Ensure campaign uses Target CPA or Target ROAS	✅
8	Verify conversion tracking is set to ‘Conversions’	✅
9	Monitor performance daily for first 3 days	⚠️
10	Schedule recurring events for next year	❌

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❓ Frequently Asked Questions

Q: What are seasonality adjustments in Google Ads smart bidding?

Seasonality adjustments allow you to tell Google Ads’ smart bidding about upcoming changes in conversion rates during events like sales holidays or product launches. They improve bid accuracy by up to 20% during peaks, ensuring your ads remain competitive without overspending.

Q: When should I use seasonality adjustments instead of manual bid adjustments?

Use seasonality adjustments when you expect a temporary change in conversion rate (e.g., Eid sale) lasting 1-7 days. Manual bid adjustments work for long-term trends. For Dhaka businesses, seasonality adjustments are ideal for events like Pohela Boishakh or Black Friday.

Q: How far in advance can I schedule a seasonality adjustment?

You can schedule adjustments up to 90 days in advance. It takes 2-3 days for smart bidding to fully incorporate the adjustment, so set it at least 3 days before the event. For Dhaka retailers, we recommend scheduling Eid adjustments 2 weeks early.

Q: Can seasonality adjustments work with Target CPA and Target ROAS?

Yes, seasonality adjustments work with both Target CPA and Target ROAS bidding strategies. They signal the model to expect a higher or lower conversion rate, helping it adjust bids proactively. A Dhaka client using Target ROAS saw a 25% ROAS lift during their peak season.

Q: What’s the difference between seasonality adjustments and conversion rate adjustments?

Conversion rate adjustments modify historical conversion rates for the model, while seasonality adjustments inform the model of future changes. Seasonality adjustments are more direct for short-term events. Use both together for maximum accuracy during major sales.

Q: How do I measure the impact of seasonality adjustments?

Compare performance during the adjustment period to the same period last year or to a baseline period. Use Google Ads’ ‘Seasonality impact’ report in Campaigns > Experiments. Look at change in cost per conversion and conversion volume. A well-executed adjustment should reduce CPA by 15-20%.

Q: Does Rafirit Station offer Google Ads management services for seasonality adjustments?

Yes, Rafirit Station provides full Google Ads management including seasonality adjustment strategies. Our Dhaka-based team helps local businesses optimize for events like Eid and Pohela Boishakh. See our services at https://rafirit.com/google-ads-bing-ads/.

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🎯 The Bottom Line

Seasonality adjustments are a game-changer for Dhaka e-commerce businesses using smart bidding. They’re not just for big budgets; even a small Panjabi store with a monthly spend of ৳50,000 can see significant improvements during Eid.

One counterintuitive insight: many advertisers think seasonality adjustments are only for large events like Black Friday. But in Bangladesh, smaller events like ‘Boi Mela’ (book fair) or ‘Eid-ul-Adha’ can deliver ROAS boosts of 40% when adjusted properly. The key is to test on a small scale first.

Don’t let smart bidding’s ‘set and forget’ mentality cost you money. By actively managing seasonality, you take control of your ad performance during the most profitable times of the year.

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⚡ Your Next Step (Do This Today)

1. Open your Google Ads account and navigate to Seasonality adjustments under Campaigns.
2. Identify your next big event (if within 90 days) or a recent past event to test.
3. Calculate the conversion rate change from baseline using last 30 days vs. event period.
4. Create a small seasonality adjustment (e.g., +20%) for a few campaigns to see impact.
5. Monitor for 3 days and compare performance to control campaigns.

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💬 Drop “seasonality adjustments” in the comments and we’ll send you our free seasonality adjustments checklist — no email required.