Climate in Iceland
The climate in Iceland is warmer than the name suggests; thanks to the Gulf Stream, which flows past the south and east coast on its way north. The summers in Iceland are cool but the winters are mild. However, the weather is very unpredictable and can change very abruptly. Good equipment and clothing is therefore essential during your holiday in Iceland.
Warm Ocean Currents
Iceland's climate is classified as being "cold oceanic" by the Köppen climate classification. The North Atlantic Ocean Current and the Irminger Current combine in making Iceland's climate more temperate than would be expected for a country situated just south of the Arctic Circle.
Winter in Iceland
The winter in Icelandic is surprisingly mild for its latitude but with notoriously unstable weather. South Iceland lowlands average around 0°C in winter, while the Icelandic highlands tend to average around –10°C. The lowest temperatures in the northern part of the Iceland range from around –25°C to –30°C. The lowest temperature on record is –39.7°C. During winter time the Aurora Borealis or Northern Lights is often very visible at night.
Summer in Iceland
The Summer in Iceland is short and mild. Closest comparison would likely be Scotland, Ireland and the Outer Islands. During summer the average temperature in the southern part of the Iceland is 10 to 3°C. Warm summer days can reach 20 to 25ºC. The highest temperature recorded in Iceland was 30.5°C in the Eastern fjords in 1939. Annual average sunshine hours in Reykjavik city is around 1300.
Winds and storm
The prevailing wind direction is easterly. Westerlies are very infrequent. Generally speaking, wind speeds tend to be higher in the highlands, but topographical features can aggravate winds and cause strong gusts in lowland areas. The average wind speed peaks at around 50 mps. The average storm wind speed is 18 mps. Heavy dust storms can be generated by strong glacial winds, and can be very strong. Up to 10 tons of material can be in motion per transect per hour. These storms are very frequent in the early summer in the arid highland areas north of the Vatnajökull glacier.
There is a persistent area of low pressure near Iceland, aptly named the Icelandic Low, found between Iceland and Greenland. This area affects the amount of air brought into the Arctic to the east, and the amount coming out of the Arctic to the west. This area is part of a greater pressure system known as the North Atlantic Oscillation.
Thunderstorms are extremely rare in Iceland, with fewer than five storms per year in the southern part of the island. They are most common in late summertime. They can be caused by warm air masses coming up from the continent, or deep lows from the southwest in wintertime. Lightning can usually be observed in connection with ash plumes erupting from the island’s volcanoes.