You'll need to stick it out until fall for the update to the new operating system, but there's no wait for MacOS Sierra's beautiful default wallpaper.
You'll need to wait a little longer for MacOS Sierra -- July for the public beta, sometime in the fall for the final release -- but you can outfit your Mac right now with a little Sierra flair. The default wallpaper for MacOS Sierra features a majestic, sun-splashed view of the Sierra Nevada mountain range and can be downloaded right now.
A high-resolution (5,120x3,684) image can be found on Apple's site, and the same size image with less sky and more mountains is available from 9to5Mac.
To set one of the above images as your wallpaper, open it in your browser, right-click on it and select Save Image As. Next, right-click on the thumbnail of the downloaded image and choose Services > Set Desktop Picture.
For more, here are all the new features coming to MacOS Sierra, learn how to sign up for the public beta of MacOS Sierra (and iOS 10) and find if you current Mac will support MacOS Sierra.
(Via OS X Daily)