Why does Microsoft only release monthly Windows patches on Tuesdays?

For over two decades – specifically since October 2003 – 'Patch Tuesday' has become a familiar practice for Windows users. These are updates released on the second Tuesday of each month, including security patches and general bug fixes for various versions of Windows. But why does Microsoft choose Tuesday, and not any other day of the week?

 

The reason is actually quite simple, especially for those working in enterprise IT environments. Microsoft intentionally avoids releasing updates on Mondays so that system administrators have time to address any outstanding issues from the previous week, or even the weekend.

Tuesday therefore becomes the ideal time. When Microsoft releases Patch Tuesday around 10 a.m. Pacific Time, IT departments will need the rest of the week to deploy the update, monitor its impact, and troubleshoot any issues that arise. Microsoft itself also closely monitors reported bugs from both enterprise and individual users, and is ready to release out-of-band patches if necessary.

 

Monthly updates also make patches more "worthwhile," comprehensive, and complete, instead of forcing system administrators to constantly chase after small, scattered patches released in rapid succession.

While the trend of integrating AI into all platforms has accelerated in recent years, Microsoft has actually been using AI-powered technologies for nearly a decade to ensure the Patch Tuesday process runs smoothly. In 2018, John Cable – Vice President of Product Management for Windows Servicing and Delivery at Microsoft – shared that the company continuously collects update experience data and retrains models to determine which devices can safely update and which need more time to ensure the best experience. Microsoft's overall goal is to deploy safe and stable updates, only accelerating them when it is truly safe.

Of course, while a release schedule that's detailed down to the day and hour helps organizations be more proactive in their preparation, it's never a perfect process. Despite planning, testing, collecting telemetry data, and user feedback, errors can still slip through. But with an operating system serving hundreds of millions of users globally, that's probably unavoidable.