Climate and weather in Iceland

Weather is ever-changing and can be forecast only a few days into the future, whereas climate is the prevailing weather condition of a region and changes more slowly. The weather must be measured for several decades to monitor changes in the climate.

Iceland lies in the North-Atlantic, just south of the Arctic Circle. The country is at the border of two main climate zones, polar and temperate, and the climate can thus be classified as cold–temperate. A warm ocean current from the south, the North-Atlantic Current, results in a milder climate than expected, given the latitude of the country. The average annual temperature in the Icelandic lowlands was in the range of 2–5°C during the time period 1980–2000. The location of the main glaciers is controlled by the high amounts of precipitation that are delivered to the south coast by southerly winds. The average annual precipitation is 4000–5000 mm (at maximum 8000 mm) in the higher elevations of Vatnajökull and Mýrdalsjökull, whereas on Langjökull and Hofsjökull it reaches a maximum of 3500 mm.

Temperature proxies from oxygen isotopes in ice cores from the Greenland ice sheet have been used to estimate past climate in the North Atlantic region including Iceland. The climate was coldest during the Little Ice Age, ca. 1450–1900. From the settlement of Iceland (about 874 CE) until the 13th century, the climate was similar to the period 1920–1960, with mean annual temperatures ca. 1°C warmer than during the coldest parts of the Little Ice Age. Few areas in Iceland have been affected by the climate fluctuations of the last few hundred years to the same extent as southeast Iceland. During the Little Ice Age, the glaciers there expanded to an unprecedented size in historical times.

Main ocean currents in the North Atlantic. Source: Stefánsson (1999). Main ocean currents in the North Atlantic. Source: Stefánsson (1999).

 

Average annual temperature in Stykkishólmur 1798–2017. Source: Icelandic Meteorological Office.

Average annual temperature in Stykkishólmur 17982017. Source: Icelandic Meteorological Office.

 

Annual mean temperatures in Iceland over the last 1100 years. Orange line, temperature proxies based on oxygen isotopes in ice cores from the Greenland ice sheet. Blue line, an estimate from Þórarinsson (1974). Source: Modified after Björnsson (2017).

Annual mean temperatures in Iceland over the last 1100 years. Orange line, temperature proxies based on oxygen isotopes in ice cores from the Greenland ice sheet. Blue line, an estimate from Þórarinsson (1974). Source: Modified after Björnsson (2017).