Microsoft plans big Windows 10 UI refresh in 2021 codenamed ‘Sun Valley'

Microsoft wants to 'reinvigorate' the Windows 10 user interface next year.

What you need to know

• A big UI refresh is on the cards for Windows 10 in 2021.
• The project is codenamed Sun Valley.
• Improvements to File Explorer, Start, and Tablet Mode are expected.

Microsoft is preparing a major OS update for Windows 10 in 2021 that sources say will bring with it a significant design refresh to the Windows UI. I'm told that Microsoft is planning to update many top-level user interfaces such as the Start menu, Action Center, and even File Explorer, with refreshed modern designs, better animations, and new features.

This UI project is codenamed "Sun Valley" internally and is expected to ship as part of the Windows 10 "Cobalt" release scheduled for the holiday 2021 season. Internal documentation describes the project as "reinvigorating" and modernizing the Windows desktop experience to keep up with customer expectation in a world driven by other modern and lightweight platforms.

Windows 10 has remained much the same these last few years, with little to no changes in its design or feature set. Many other platforms on the market have gone through entire redesigns or UI refreshes in the last five years, and while Windows 10 has gone through minor design iterations with the introduction of Fluent Design, we've not seen a significant refresh or rethinking of its UI.

The Sun Valley project appears to be spearheaded by the Windows Devices and Experiences team, lead by Chief Product Officer Panos Panay, who took charge of said division back in February. Microsoft announced in May that the company would be "reinvesting" in Windows 10 in the 2021 timeframe, and my sources say that Sun Valley is the result of that reinvestment.

What can we expect?

It's still too early to nail down exactly what will be updated with Sun Valley, but sources have said to expect new Start menu and Action Center experiences, likely based on those same experiences found on Windows 10X, but tailored for desktop. Microsoft is also working on an updated Taskbar built with modern code, and an improved UI for the legacy File Explorer.

For tablet users, I'm told that better animations and a more "fluid experience" is on the cards. We already know that Microsoft is redesigning the touch keyboard and emoji picker, as those changes are already live in the Windows Insider Dev Channel. Microsoft will also continue its escapade of rounding-off corners throughout the UI, including app windows and other shell areas.

Sources also say to expect a wider adoption of WinUI throughout the Windows Shell and in-box apps, which should provide subtle yet improved design changes. In addition, more legacy UI areas are expected to get dark mode support in an effort to make the Windows UI look and feel more consistent when using Windows 10's dark theme.

I understand that this refreshed design will be an evolution of Fluent Design, and likely still called Fluent Design. Microsoft isn't introducing a new design language with Sun Valley, it's simply refreshing and refocusing the current one on desktop, and trying to apply it more consistently throughtout the OS, a big feat for the legacy Windows desktop.

When is the release date?

It's important to stress that Microsoft can cut or delay these plans at any time between now and when the update ships next year. It's likely that some of these plans won't it to the final product, as that's just the nature of Windows OS development, and the reason why Microsoft doesn't announce these plans ahead of time. But, these are the things Microsoft wants to deliver to Windows 10 customers next year.

Microsoft is hoping to have most of this work done by the end of the Cobalt development semester, which wraps up in June 2021. Microsoft will then RTM a build, ship that off to OEMs and begin testing it in the Beta Channel as a designated release. The update itself won't roll out to the public until the fall, likely with an LCU (latest cumulative update) which sits on top with last-minute features and fixes.

If Microsoft is able to pull off its plans with Sun Valley, this will be the biggest Windows 10 UI refresh we've seen so far, coming after three long years of Windows 10 sitting on the back burner. Panos Panay wants people to go from needing Windows to loving Windows, and a modern refreshed interface that's intuitive and design-driven is a great start.

With Sun Valley, Windows 10 will still be familiar to PC users, unlike the transition from Windows 7 to Windows 8. I'm also told that for some features, users will be able to switch between the new and old experiences, giving users a choice rather than forcing it upon them. Sun Valley is all about improving and modernizing the familiar Windows UX, and not radically changing it up.

For now, what are your thoughts on Microsoft's Sun Valley project? Let us know in the comments.