Does migrating to HTTPS always cause a temporary drop in traffic?

What actually happens during an HTTPS migration?

When a site switches from HTTP to HTTPS, Google technically treats each HTTPS URL as a new URL. The old HTTP URLs disappear from the index to be replaced by their secure equivalents. This process is not instantaneous.

Between the moment Googlebot discovers the redirects and when all ranking signals are transferred to the new URLs, a floating period occurs. Backlinks still point to the old URLs, PageRank must transit through the 301 redirects, and performance history needs to be associated with the new URLs.

Why aren’t redirects enough to prevent any drop?

A well-configured 301 redirect passes about 90-99% of link equity according to field observations. But this transfer takes time. Googlebot must recrawl the old URLs, follow the redirects, and then reassess each page in its new HTTPS context.

During this phase, some pages may temporarily coexist in the index under both versions, creating mixed signals. The engine must also check that SSL certificates are valid, that there are no mixed resources, and that the HTTPS configuration is clean.

How long does this transitional period last?

Google does not provide a precise duration, but field observations show between 2 and 8 weeks depending on the size of the site and its crawl frequency. A site with a high crawl budget recovers faster than a small site with infrequent updates.

The speed of reindexing also depends on the technical quality of the migration: clean redirects, absence of redirect chains, updated XML sitemaps, and submission of the new URLs via Search Console accelerate the process.

• HTTPS Migration = new URLs that need to be fully reindexed, not just a simple switch
• The transfer of signals via 301 takes several weeks, even with a perfect configuration
• Crawl budget and update frequency directly influence the duration of the drop
• 301 redirects transfer most but not 100% of equity immediately
• A drop of 10-30% for 2-4 weeks is within the normal range

Does this statement really reflect what is observed in the field?

Yes, and it is even a rare case where Google is perfectly aligned with practitioner experience. All the HTTPS migrations I have managed or audited showed this temporary drop. The extent varies according to the technical quality, but even perfect migrations lose 5-15% for a few weeks.

What is missing in this statement is the notion of differential severity across niches. An e-commerce site with high seasonality migrating in November can face catastrophic business impacts from a technical drop of 20%. Google never nuances this point.

What are the real aggravating factors that Google doesn’t mention?

The statement remains vague about what turns a normal drop into a disaster. Redirect chains (HTTP → HTTPS → new structure) multiply the loss. Mixed resources (images, CSS, JS still on HTTP) break browser trust and slow down indexing.

A rarely discussed point: the timing of migration massively influences the perceived impact. Migrating during an algorithm update or just before a seasonal peak makes it impossible to distinguish the causes. I’ve seen clients attribute a drop to HTTPS that was actually caused by a simultaneous Core Update.

When does this rule not apply?

Very small sites (fewer than 50 pages) with frequent crawling can recover in just a few days. Conversely, sites with millions of pages and a limited crawl budget may stagnate for months if sitemaps and prioritization are not optimized.

Another case: sites already partially on HTTPS (only certain sections) undergo a less brutal migration since Google already knows some of the secure URLs. The signal transfer is then more gradual and less visible.

What should be implemented before migrating to HTTPS?

Before any migration, establish a performance baseline over at least 4 weeks: organic traffic by page template, positions of strategic keywords, crawl rate in Search Console. Without a proper reference, it’s impossible to measure the actual impact.

Configure the 301 redirects one by one for each URL, never a global redirect to the home page. Test each redirect manually or using a crawler like Screaming Frog to ensure that no chains have been created and that all HTTP codes are correct (301, not 302).

How to speed up reindexing after migration?

Immediately submit new HTTPS XML sitemaps via Search Console after removing the old HTTP ones. Force recrawl of strategic URLs using the URL inspection tool. Temporarily increase publication frequency to boost the crawl budget.

Monitor server logs to ensure that Googlebot is actively crawling the new HTTPS URLs and following the redirects properly. If the bot remains stuck on the old HTTP URLs beyond 72 hours, a technical issue exists (robots.txt, contradictory canonicals, poorly configured redirects).

What critical errors must be absolutely avoided?

Never leave both versions coexisting without redirection. All HTTP URLs must redirect in 301 to HTTPS, including any old 404 URLs that had backlinks. Check that no canonical tags still point to HTTP after the migration.

Avoid migrating during a high seasonality period or just before a known algorithm update. The timing can turn a manageable technical drop into a business catastrophe. Plan the migration during a slow period where a 20% drop for 3 weeks remains manageable.

• Establish a traffic and position baseline for a minimum of 4 weeks before migration
• Configure individual 301 redirects URL by URL, testing each redirect
• Update all XML sitemaps and submit them via Search Console immediately
• Eliminate all mixed resources (images, CSS, JS) before launching HTTPS
• Monitor server logs to verify active crawling of new URLs within 48-72 hours
• Plan for 2-8 weeks of a 10-30% drop in business projections and compensatory AdWords budgets