UK: Was summer 2018 the hottest on record?
Update: Having further assessed the temperature data for the UK as a whole for summer 2018 the figures are so close that we are declaring it as the joint hottest on record together with 2006, 2003 and 1976.
The margin between the mean temperatures at the top of the league tables (records dating back to 1910) is so small, at around 0.03 of a degree, that it is impossible to separate the years.
Usually we will only quote statistics to the nearest 0.1C as differences smaller than this could result from small numerical differences arising from the statistical calculations. The provisional temperature for the summer of 2018 is nominally 15.80C, for 2006 is 15.78C, for 2003 is 15.77C, and 1976 is 15.77C all of which are within 0.03C of each other, and will therefore be quoted as 15.8 °C.
With margins as small as these we will inevitably see different rankings across the nations and regions of the UK and the different datasets held by the Met Office – such as the Central England Temperature* (CET). However, 2018 was clearly the warmest summer on record for England, with a provisional figure of 17.1C as of 31 August on the Met Office's mean temperature measure for the whole country, beating the 17.01C of 1976.
Press Release issued Friday 31 August 2018
With one day to go, it is clear that 2018 has been one of the hottest summers on record for the UK, however, the margin between the mean temperatures at the top of the league tables (records dating back to 1910) is so small that at this point it is impossible to say if 2018 will be an outright winner. It is very close to the record-breaking summers of 2006 (15.78C), 2003 (15.77C), and 1976 (15.77C) all of which are within 0.01C of each other.
The margin is so small that different datasets and different regions of the UK will have different ranking. Usually we will only quote statistics to the nearest 0.1C as differences smaller than this could result from small numerical differences arising from the statistical calculations. A more comprehensive analysis of the 2018 summer data will be undertaken early next week and data for summer 2018 will continue to be analysed over the coming months.
However, it looks more likely that it could be the warmest summer on record for England with the mean temperature standing at 17.2 C with one day to go, which would narrowly beat the record set in 1976 (17.0C). It is not going to be a record for Scotland, Northern Ireland or Wales where the records stand at 14.1C (2003), 15.5C (1995) and 16.1C (1995), respectively.
To get an even longer-term perspective our multi-century Central England Temperature* (CET) series dates back to 1659. In this dataset summer 2018 looks likely to slip behind the summers of 1976 and 1826. If we look back through the CET series only 10 summers recorded an average temperature above 17C. Six of those have occurred since 1976, and only two (1826, 1846) were pre 20th Century, which is consistent with the general picture of our warming climate globally and here in the UK.
Summer 2018 was notably dry and sunny too. For the UK it is likely to finish in the top 15 driest summers, and top 5 driest for England. It is also in the top 5 sunniest for the UK.
August
After a hot June and July, August turned out to be closer to average with the mean temperature less than half a degree above average and rainfall 8% below average for the UK as a whole. Rainfall varied across the country with areas such as Banffshire, Denbighshire and Anglesey getting around half of the expected August rainfall while areas such as Berwickshire and Sussex getting around 30% above average.
Looking ahead into the start of autumn high pressure is likely to, once again, often be dominating the UK weather with plenty of warm, dry and sunny days for many through the first part of September. More unsettled spells of weather are expected at times, particularly from mid-month.