Analysis map of Iceland 22 July 2012 at 21:00 hrs which shows a low pressure record for July, represented by the number 728 which equals 972,8 hPa. The number 728 can be seen just to the right and above Westman islands, Vestmannaeyjar, south of Iceland. Roughly parallel solid lines show air pressure with an interval of 1 hPa.

A new low pressure record for July in Iceland

More than a hundred years record beaten

23.7.2012

A remarkably deep low developed to the southwest of Iceland on 19 and 20 July 2012. According to the analysis of the ECMWF the central pressure in the low dropped to 966 hPa. This is amongst the lowest values ever observed in the North Atlantic in July.

After the low reached its maximum intensity it moved towards Iceland and filled gradually. In the evening of Sunday 22 July the pressure was at minimum near the south coast of Iceland. The lowest mercury barometer reading was 972.8 hPa, first at Vestmannaeyjar at 21 pm and then again at Kirkjubæjarklaustur 6 hours later. The lowest value at an automatic station was reached in Vestmannaeyjar during an extended period of one hour, 21:30 to 22:30, 972.4 hPa.

The pressure in Iceland has only on three occasions dropped down to 975 hPa or lower in the entire record extending back to the 1820s. These cases were 974.1 hPa in Stykkishólmur on 18 July 1901, 974.3 hPa in Stykkishólmur on 19 July 1923 and 975.0 hPa in Reykjavík 11 July 1912.

It should be kept in mind that although the pressure was recorded at a few stations all over the country during the period from 1874 onwards, longer intervals passed between readings than now. Three readings per day were typical, but eight readings have been made at most of the barometric stations since the mid-1940s.

Now, automatic instruments are replacing the old mercury barometers at the stations.