Google announced in a Google+ post that starting today Google Now notifications will be available to Chrome users on their desktop or laptop computers. To enable this feature, simply sign in to Chrome with the same Google Account you’re using for Google Now on Android or iOS. Remember, it's a two-way system. If you use Google Now on your Android device, then only you can see certain cards on your desktop computer if you're signed into Chrome, including weather, sports scores, commute traffic, and event reminders cards.
If the notifications isn't appearing on your PC then you may have to wait. The company is rolling out the feature over the next few weeks.
Screenshot of Google Now notifications: