The NC500 is one of Scotland's most popular road trips, taking in 500 miles of coastal roads in the far north of Scotland. April, May and September would be the best time to undertake this epic trip.
Daylight hours will be longer for more sightseeing, the roads won't be blocked with snow, and tourist numbers should be fewer outside of the high season. The NC500 has been a victim of its fantastic promotional campaign, and travelling it in the height of summer may detract from your experience due to the sheer number of people on the road.