Thanks to being an isolated island reached by the Gulf Stream, Iceland enjoys a temperate maritime climate, with refreshing summers and surprisingly mild winters. However, the island is located right at the Arctic Circle, and its weather is also affected by the East Greenland polar current, which curves southeastwards off the north and east coasts. The wind direction is thus highly influential.
While temperatures fluctuate only a little from night to day or season to season, precipitation often begins unexpectedly and breezes can add to the cold. Tourists should be prepared even in summer for chilly, wet, windy days; in winter, blizzards may suddenly delay their travel plans, and blowing sand in windstorms or late thaws in the highlands might affect their plans even in summer. As the locals will reassure them, however: if you don’t like the weather, just wait a bit.
Iceland has short, cool summers and long but mild winters, while wet periods may occur in some area of the island at any time of the year, even when the opposite side of the island or of a mountain range remains dry. From June to August, visitors can expect average monthly temperatures of around 10-13 °C (50-55 °F). Even if the island has of course felt the effects of climate change, experiencing a general upward drift in average temperatures, the warmest days are unlikely to peak above 20-25 °C (68-77 °F). The middle of the year features the midnight sun. Due to its flat trajectory along the horizon, the island never grows fully dark during what most Western countries call late spring and early summer. On July 1 in Reykjavík, for example, even if the sun sets at 23:57 and rises again at 03:04, it stays amazingly light outside the whole time. This effect is even more pronounced in the north of the country, where you can easily get around with constant 24-hour lighting from early May to early August, after which the lengthening nights of winter, in clear weather away from town lights throughout the island, are often decorated by the northern lights.
Despite the country’s high northerly latitude, Iceland’s winter temperatures are relatively mild. The southern lowlands have monthly averages of around 0 °C (32 °F) in the dead of winter, while even the much colder highlands tend to average only around -10 °C (+14 °F). Snow is commonplace, and can be seen both as an exciting attraction as well as a possible hindrance to travel. In the northern half or so of the island, winter snow is assured enough to open a variety of adventure and sporting opportunities, particularly in higher reaches.
On the warmer and particularly on rainy, wet days in all of the lowlands, above all in more southerly regions, such snow can melt away again in short order even in mid-winter, or else partially melt and then freeze into hard, slippery ice. Even if Iceland’s temperature figures are not so extreme, conditions are sometimes harsh and hazardous, with snow storms or near-freezing rain in strong winds common throughout the colder months. Travellers should always check the weather forecast and road conditions before setting out on their journey, preferably even discussing them with the locals, and show full consideration for road closures or warnings.
Winter days are short, although they nowhere remain dark for the whole time. On 1 January in Reykjavík, the sun rises at 11:19 and sets at 15:44. While the hours of potential direct sunlight are shorter farther north on the island, twilight lasts substantially longer everywhere than nearer the earth’s equator. Also, although skies may be dark, Icelanders brighten up the winter days with twinkling fairy lights, warm cosy cafés, a variety of sports and a packed schedule of winter festivities. Every winter traveller ought to try the swimming pools, for instance meeting the locals in a hot tub and watching the snowflakes melt when approaching the surface.
The spring and autumn nights and days are more similar in length to each other. High winds and stormy weather, however, may be somewhat more common in the spring and autumn seasons. In northerly regions, snow and wintry conditions are still likely to occur on occasion in May or even early June, and at higher altitudes in every month of the year. Finally, one might note that Icelanders do not follow any exact splitting of the year into four seasons, but on calendars only show a summer half and winter half. Summer officially begins on the First Day of Summer, which is on the last Thursday in April, and the summer is actually supposed to turn out better, according to old beliefs, if there is frost on that morning.