I think the incoming temporal storm should be indicated by something other than just a chat message. Your temporal stability meter should start swinging back and forth wildly and have a rift effect around it or something, getting more intense over time. Also, the rift activity could steadily increase up to apocalyptic as the storm gets closer, naturally giving the player an idea of what is about happen.
I love how you can see the dark clouds of a thunderstorm blowing in on the horizon, so temporal storms should be given the same level of detail.