By Rick Steves and Ian Watson
Your Icelandic experience will vary drastically depending on the time of year.
Summer really is the best time to go — even if everyone else is there with you. From June through August, days are long and the weather is at its best. At these northern latitudes, from about June 1 to July 15, the sun dips below the horizon for only a few hours, and it never really gets dark. Icelanders take full advantage of these days of "midnight sun," and so should you. July and early August usually bring a few T-shirt days, with temperatures climbing into the 60s and sometimes even breaking 70. After mid-August, it rapidly gets colder and darker, and things quiet down.
May and September can be a decent compromise in terms of crowds and weather. May is bright, with the solstice nearing, but it's chilly. September brings subtle fall colors to the fields and hillsides, and as evenings darken, the first glimpses of the northern lights. Keep in mind that as late as May or as early as September, snow and extreme weather can disrupt your plans, particularly on higher-elevation roads (remote areas are accessible only from late May to early September).
Days are short from mid-October to mid-February — the sun rises after 11:00 all December — and dusk will draw the shades on your sightseeing well before dinner. You can still enjoy a stopover in Reykjavík, though. Christmastime activities (including bonfires and fireworks on New Year's Eve) offer a warm experience at a frosty time. In these months, bus trips to the nearby Golden Circle and South Coast are typically still possible (leave winter driving to the pros). Driving the Ring Road in winter is inadvisable at best, and impossible at worst.
One benefit of a winter visit is the chance to view the elusive northern lights, though whether you'll actually see them is unpredictable. Weather, location, and luck all play a part.
Ian Watson is the co-author of the Rick Steves Iceland guidebook.