The best time to visit Kangerlussuaq largely depends on whether you're hoping to experience the Northern Lights or the Midnight Sun, as each offers a distinct experience.
For those eager to witness the spectacular Northern Lights, the period between September and April is ideal. During these months, the nights are long and dark, providing the best conditions for viewing the aurora borealis. Kangerlussuaq, with its typically clear skies and inland location away from coastal fog, is considered one of the prime spots in Greenland for this natural phenomenon.
If you're more interested in the Midnight Sun and extended daylight hours for outdoor activities, then the summer months from June to August are perfect. During this time, the sun barely sets, allowing for long hikes and explorations of the surrounding Arctic landscape well into the evening. This period is also when the temperatures are mildest, making it comfortable for excursions to the Greenland Ice Sheet or wildlife spotting.