An unusually intensive high-pressure system is now (28 March 2020) situated to the south of Iceland. The highest sea level pressure value (slp) observed in Iceland today was 1050.5 hPa - at the station Hjarðarland in the southern lowland. This is the highest slp observed in Iceland since 16 April 1991 (1050.8 hPa) and the second highest slp in the month of March. The record is 1051.7 hPa, measured at Vestmannaeyjar 6 March 1883. 

It should be noted that still higher values were nominally noted in the central highlands, the highest value 1054.2 hPa at the station Setur [695 m a.s.l). This high value is a result of a dubious reduction of the pressure down to sea level in light winds and very low temperature (-19°C) and will thus not be confirmed as a record value. 

Pressure values above 1050 hPa are only seldomly seen in Iceland. The record is 1058 hPa, measured in Reykjavik on 4 January 1841 (uncertainty probably about 2 hPa) and the second highest measured in Stykkishólmur 16 December 1917, 1053.3 hPa (but possibly 1054.0 hPa). There are 11 known instances of a higher value than the one reached today, 1 in April, 1 in March, 3 in February, 4 in January and 2 in December. In some of the cases the high values were measured at more than one station. 

A record breaking "heatwave" passed Iceland last evening and night. It didn't last long but resulted in a new national maximum temperature record for December, 19.7°C at the station Kvísker, situated below the east flank of Iceland's highest mountain, Öræfajökull. The old national record was 18.4°C measured at Sauðanesviti at the north coast on 14 December 2001. This maximum was now exceeded at two other stations besides Kvísker, both in the northern part of the Eastern fjord area - near the easternmost point of Iceland, Bakkafjörður (maximum = 19.0°C) and Seyðisfjörður - Vestdalur (maximum 18.8°C).

This was due to an northerly excursion of very warm air from the south. According to the analysis of the ecmwf the 500/1000 hPa thickness over eastern Iceland exceeded 5540 meters, might be the highest December value on record for the area - but needs verification. According to the same source the potential temperature at 850 hPa reached 26.3°C at the same time. - Even so, the high temperatures at "ground level" is unusual but probably made possible by the lack of snow in the area and relatively dry ground after a very dry November, generally the driest since 1952 in the Northern part of the country.

Daily (calendar date) maxima were recorded at more than 200 stations, at stations with more than 10 years of observations the records were 178 on the December 2, 111 on December 3 and 20 on December 1.

Previous records for the whole month of December were exceeded or equalled at 53 automatic stations (more than 10 year of observations) and on three manned ones. At Akureyri in the north maximum temperatures have been recorded for 80 years (but temperature has been measured there much longer). During these 80 years the highest maximum was 15.1°C. This was exceeded now as the maximum thermometer this morning (3 December) was at 15.5°C.

At the automatic stations the temperature is averaged over 2 minutes (thought to be comparable to the response time of a mercury thermometer), every 10-minutes there is a registration of the highest and lowest temperature during the preceding 10-minutes - the highest thus becomes the maximum of these 10-minutes. The figure shows the 10-minute maximum temperatures at the two stations that registered the highest maxima during this event, Kvísker and Bakkagerði during a 36-hour interval from 2 December to noon on 3 December. The rapid rise in temperature at both stations is notable - increasing wind then "exposes" the warm air aloft as it extends down to station level.

The second figure shows the temperature at Seyðisfjörður - Vestdalur (92 m a.s.l.) and Gagnheiði (949 m a.s.l.), the stations are located close to each other, one in a valley near a narrow fjord in the Eastern fjords area and the other on an exposed, but not steep, mountaintop nearby. The green trace shows the temperature difference between the stations. One might note that the temperature on the mountain is not as variable as down in the valley and the warm air aloft "struggles" to reach the valley bottom - during a short period the temperature on the mountain is higher than in the valley - even the altitude difference is about 850 meters.

April 2019 was unusually warm in Iceland. In most of the West and North it was the warmest one on record and the second warmest in the country as a whole. The average temeperature in Reykjavík was 6.5°C, +3.6°C higher than the 1961-1990 mean and +0.2°C higher than the previous record (in April 1974). In Stykkishólmur in the west the average in April was 5.8°C, +4.2°C above the 1961-1990 mean - also a new record. In Akureyri April was also the warmest of all time with an average of 6.9°C, +5.3°C above the 1961-1990 mean. 

The warm weather was "caused" by an unusually persistent spell of Southeasterly winds lasting almeost the whole month (except for the first few days). 

The map shows the average 500 hPa-height in April (ecmwf-analysis - map by Bolli Pálmason) and the very large deviation [colours], positive to the NE of Iceland and negative to the SW. 

On the 30th the temperature in Reykjavík reached a new record maximum for April, 17.1°C, the former record, 15.2°C was old, from April 29 1942. 

Some readers might want to check on links to texts about the situation in Icelandic [google translate might or might not be helpful]: The monthly report of the Icelandic Meteorological Office, Tíðarfar í apríl 2019, and two blogs on "hungurdiskar",  Óvenjulegur apríl í háloftunum [an unusual upper-air April] and Meir af apríl [More on April - a discussion of the circulation and its part in the record].

Temperatures above 25°C are rare in Iceland in September and have only been registrered on a few occasions. On 1 September (2017) the maxmimum at Egilsstaðir airport reached 26.4°C. This is 0.4°C higher than the previous Icelandic record, measured at Dalatangi on 14 September 1949. The Egilsstaðir automatic station has been in place since 1998, but previously, manned synoptic observations had been made on the site or in the nearby village since the late 1940s. The first years of observations there were of dubious quality, but are considered to be reliable from 1955 onwards.

Egilsstaðir is a favoured site for high temperatures during summer and have measured higher temperatures than 26°C in June (max. 26.7°C), July (28.8°C) and August (29.2°C). The previous high in September was 22.0°C.

Location of Egilsstaðir: 65°16.571'N, 14°24.276'W, 23.5 m above sea level.

On 1 September many stations in the North and East part of the country topped their previous September maxima.

The highest temperature measured in Iceland this summer is 27.7°C, at the station Végeirsstaðir in the North on 25 July and was the highest temperature measured in Iceland since 2012.

The Icelandic Meteorological Office has issued its official statement of the climate in Iceland in 2014 in English. In the Eastern part of the country and in some of the northern areas as well it was the warmest year ever measured and in the rest of the country it was generally the second or third warmest, slightly exceeded by the temperature in 2003 or 1933.

It was the 19th consecutive year of above normal annual temperature in Reykjavík (vis. 1961 to 1990). The annual temperature in Surtsey, 7.2°C is the highest annual mean temperature ever registered at an Icelandic weather station, exceeding the temperature at the same site in 2010 by 0.1°C.

In spite of the high temperatures the weather was changeable and often dull. The first months of the year were especially wet in the North and East and the weather was difficult. In the west it was very dry at the same time with favorable weather conditions. The summer was warm and considered fine in the North and East but in the south it was very wet and dull. The autumn was fine, November extraordinarily warm, but the year ended with an unruly and a rather cold December.

The precipitation in 2014 was above normal at most stations, as was the number of days with precipitation. Snow was light in Reykjavík, as generally in the South and West. Snow covered the ground in Reykjavík for 41 days during 2014, 24 days less than average. The snow was heavy in Akureyri in and covering the ground for 133 days during the whole year 2014, 16 days more than average.

There was less sunshine in Reykjavík and Akureyri than during the recent years, about 100 below the 1961 to 1990 average at both locations and 200 below the average of 2004 to 2013.

The average sea level pressure in Reykjavík was 1001.7 hPa, 4.2 hPa below the average 1961 til 1990. In the long term it is rather low, but the annual pressure in 2011 was lower still.

The wind speed was close to the average for the year as a whole, but December and February were very windy, June was unusually calm. Easterly and Northerly winds were unusually persistent in January and February, westerly and southerly winds were prevalent in September and easterly in November.