30 days on either side of the peak of winter (21st of December) daylight is limited and that can make seeing things more difficult. The sun rises not very far from the horizon between 11am and 4pm but enjoyment of most activities will primarily depend on what you plan on doing and how lucky you get with the weather. It’s very unpredictable, even hour by hour, so you’re at the mercy of nature to have good visibility from frequent snow storms.
As a tourist in Winter, you’re probably best to be taking guided excursions from Reykjavík and not backpacking the highlands or driving the ring road in a camper van. Those activities could in fact be very dangerous if you aren’t prepared.
