Many have found that the weather tile for the Microsoft Band no longer updates automatically.
Originally, the weather tile was supposed to deliver updates every 15 minutes or so. It does this by connecting to the Microsoft Health app in the background. However, due to various issues like Microsoft trying to fix battery life when Microsoft Health was running and other things, this function is no longer automatic.
You can get the weather to update, but you have to open Microsoft Health and sync with your Microsoft Band manually. Not very convenient and not the way its supposed to work, I agree, but...
And, incidentally, this is on any supported platform (Android, iOS, Windows Phone/Mobile) and not just Windows 10 Mobile builds – which seems to be the worst of the bunch.
I’ve reached out to the Microsoft Band team to see if this might be updated sometime soon.