Iceland has a subpolaroceanic climate (Köppen climate classificationCfc)^[1] near the southern coastal area andtundra (KöppenET) inland in the highlands. The island lies in the path of theNorth Atlantic Current, which makes its climate moretemperate than would be expected for itslatitude just south of theArctic Circle. This effect is aided by theIrminger Current, which also helps to moderate the island's temperature.^[2] The weather inIceland is notoriously variable.^[3]

Theaurora borealis is often visible at night during the winter. Themidnight sun can be experienced in summer on the island ofGrímsey off the north coast; the remainder of the country, since it lies just south of thepolar circle, experiences a twilight period during which the sun sets briefly, but still has around two weeks of continuous daylight during the summer.

The Icelandic winter is relatively mild for its latitude, owing to maritime influence and proximity to the warm currents of theNorth Atlantic Gyre. The southerly lowlands of the island average around 0 °C (32 °F) in winter, while the north averages around −10 °C (14 °F). The lowest temperatures in the northern part of the island range from around −25 to −30 °C (−13 to −22 °F). The lowest temperature on record is −39.7 °C (−39.5 °F).^[4]

The average July temperature in the southern part of the island is 10–13 °C (50–55 °F). Warm summer days can reach 20–25 °C (68–77 °F).^[4] The highest temperature recorded was 30.5 °C (86.9 °F) in theEastern fjords in 1939. Annual average sunshine hours inReykjavík are around 1300, which is similar to towns in Scotland and Ireland.^[5]

Iceland, especially inland and during winter, is frequently subject to abrupt and dramatic changes in weather that can sharply reduce visibility, as well as rapidly increasingwind speed andprecipitation, and shift temperature.

Generally, wind speeds tend to be higher in thehighlands, buttopographical features can aggravate winds and cause strong gusts in lowland areas. Wind speed in the lowlands reaches 18 m/s (65 km/h) on 10–20 days per year, but on upwards of 50 days per year in places in the highlands.^[4] The strongest measured 10-minute sustained wind speed is 62.5 m/s (225 km/h) and the strongest gust 74.2 m/s (267 km/h).^[6] Heavydust storms can be generated by strongglacial winds, and can be very strong. Up to 10 tonnes (11 short tons) of material can be in motion pertransect per hour. These storms are very frequent in the early summer in the arid highland areas north of theVatnajökull glacier.^[7]

Thunderstorms are extremely rare for any specific location in Iceland, with fewer than five storms per year in the southern part of the island. They are most common in early or late summer. They can be caused by warm air masses coming up from Europe, or deeplows from the southwest in wintertime.Lightning can usually be observed in connection with ashplumes erupting fromthe island's volcanoes.^[8]Vortices, sometimes on the scale oftornadoes, also occur with volcanic eruptions.Landspouts andwaterspouts are occasionally observed. Classicmesocyclone derived tornadoes (i.e. forming fromsupercells) are very rare, but have been observed. Any of these do occasionally cause damage, although the sparse population further reduces the probability of detection and the hazard.^[9][10]

There is a persistent area of low pressure near Iceland known as theIcelandic Low, found between Iceland andGreenland. This area affects the amount of air brought into theArctic to the east, and the amount coming out of the Arctic to the west.^[11] It is part of a greater pressure system known as theNorth Atlantic Oscillation (NAO).^[12]

Due toclimate change, Iceland is experiencing fasterglacial retreat, changing vegetation patterns and shifting marine ecosystems.^[24] Although Iceland ranks relatively low internationally in absolutegreenhouse gas emissions, producing approximately 49 tonnes in 2023, it ranks within the top 25 countries for emissions per person.^[25] Iceland’s main energy sources aregeothermal andhydropower, with fossil fuels mostly utilized in the transport sector.^[26] Iceland has committed to reachingcarbon neutrality before 2040.^[27]

750 square kilometers of Iceland’s glacier ice has melted since the year 2000.^[28] Iceland’s annual CO₂ emissions and per capita CO₂ emissions rose from 1950 to 2018,^{[by how much?]} but both metrics have been on the decline since 2018. A majority of Iceland’s CO₂ emissions come from oil.^[29]

Most Icelandic glaciers began retreating in the late 1800s, but current modeling studies suggest that glaciers would lose a quarter of their volume in the next hundred years with just a 1°C rise in global temperatures. The models also predict that glaciers could lose sixty percent of their volume if global temperatures rise by 2°C. At this rate, only small ice caps will remain after two hundred years.^[30] Some models predictIceland's glacial mass will shrink a third by 2100.^[31]

Iceland’s retreating glaciers have global and local consequences. Melting of Iceland’s glaciers could raise sea levels by a centimeter,^[32] which could lead to erosion and flooding worldwide.^[33] Locally, glacial recession could cause crustal uplift,^[32] which could disrupt buildings. Some places in Iceland have already seen the crust rise at a rate of 40 millimeters per year.^[32]

Okjökull was a glacier in Iceland that melted in 2014. Okjökull was Iceland's first glacier to have melted due toclimate change.^[34]

Geologists estimate thatOkjökull covered about 6 square miles in the late 1800s,^[35] but slowly shrank until it officially lost its glacier status in 2014. When it "died", the 800 year old^[35] glacier's name was changed from Okjökull to Ok. Okjökull was pronounced dead in part due to its decrease in area, but also due to its inability to flow;^[36] a body of ice must be able to move to be defined as a glacier.^[37] “Jökull” means glacier in Icelandic,^[38] so this suffix was removed accordingly.

In 2018, a documentary calledNot Ok was released by Rice University anthropologists four years after its death.^[39] In 2019, roughly one hundred people held a funeral for Okjökull. Iceland’s prime minister at the time,Katrín Jakobsdóttir, was among the attendees.^[39]

At the funeral, one high school student read a poem and a commemorative plaque, titled "A letter to the future,"^[40] was placed on a boulder. As of 2022, this plaque was the only one commemorating a glacier lost toclimate change.^[40] The plaque warned future readers that all of Iceland's glaciers would soon "follow the same path" as Okjökull.

In an effort to combat the effectsclimate change has on Iceland’s glaciers, Iceland has worked to make its electricity completely sustainable. As of 2015, nearly all of its electricity comes from renewable energy. Thirteen percent of the country’s electricity comes from geothermal energy—which also heats ninety percent of Iceland’s homes—and the rest comes from hydropower.^[41]

• Climate of the Nordic countries
• Geography of Iceland

Wikimedia Commons has media related toWeather and climate of Iceland.

• The dynamic climate of Iceland – A brief description of the country's climate (with maps)
• Reykjavík, Iceland Forecast: Weather Underground – Weather forecast for Reykjavík

• Climate of Iceland
• Climate by country

• CS1 Icelandic-language sources (is)
• Articles with short description
• Short description is different from Wikidata
• Wikipedia articles needing clarification from January 2023
• Commons category link is on Wikidata