The International Space Station is only visible on certain dates
The ISS has been around for more than a decade. Despite its age, it can be said that it is only now coming into its own as the astronauts above it can dedicate all of their time to science experiments and not to building or expanding the station.Despite seeming common place, it's still one of man's greatest achievements and, because it's actually so close to Earth, it's probably the only one that almost anyone around the world can see as it flies by.
Amateur astronomers and enthusiasts have had no problem keeping track of it and it is relatively easy to determine when it's going to fly over your head.
Still, it requires a bit of technical knowledge. But now, NASA has made it possible for anyone to find out when the ISS is above and how to spot it.
You can sign up for email or, in some places, SMS alerts and be notified when the ISS is near, either in the evening or in the morning.
Depending on where you are, you may get to see the ISS every day for a week and then not at all for a few more weeks. There are other resources online to help you plan ahead.