The night sky is dark enough for the aurora to be seen from about mid-September to early April.
In Kiruna there is a nice natural area behind Camp Ripan, where you can avoid disturbing city lights, in order to see the Aurora.
Another nice place where the chances are good is Aurora Sky Station in Abisko, which is open between 20.00-24.00 on Tuesdays to Saturdays during October until March. For more specific information, please check www.auroraskystation.se.