Summer has barely begun, but temperature records are already being broken. Data released today show that the European-average temperature for June 2019 was higher than for any other June on record. Average temperatures were more than 2°C above normal and it has become the hottest June ever recorded.

Although not as persistent as that of summer 2018, this short heat wave, caused by a mass of hot air coming from the Sahara Desert, was intense. The five days of unusually high temperatures followed days with record-breaking temperatures further east in Europe. This led to the month as a whole being around 1°C above the previous record for June, set in 1999, and about 1°C higher than expected from the trend in recent decades.

Map showing the anomalies in temperature (°C) estimated from ERA5 during the 5-day period of 25-29 June 2019. (Credit: ECMWF, Copernicus Climate Change Service).

Data provided by the Copernicus Climate Change Service (C3S), implemented by the European Centre for Medium-Range Weather Forecasts on behalf of the European Union, show that the global-average temperature for June 2019 was also the highest on record for the month. It was about 0.1°C higher than that of the previous warmest June, in 2016, following a strong El Niño event.

The map of temperature anomalies shown above, based on the latest C3S data, highlights just how unseasonably warm the end of the month was. Compared to the average for the same five days during 1981-2010 (the standard 30-year climatological reference period), temperatures of 6-10°C above normal occurred over most of France and Germany, northern Spain, northern Italy, Switzerland, Austria, and the Czech Republic.

Average June temperatures (°C) for Europe (top) and globally (bottom) from 1979 to 2019, shown as differences from long-term average values for 1981 to 2010. June 2019 is highlighted. Data source: ERA5 (credit: ECMWF, Copernicus Climate Change Service).

Although it is difficult to directly attribute this heat wave to climate change, such extreme weather events are expected to become more common as the planet continues to warm under increasing greenhouse gas concentrations.

Looking at the temperature data from a longer-term perspective reveals the month to be even more unusual. Merging the latest C3S data with datasets that extend further back in time shows that the June 2019 European-average temperature was more than 3°C higher than the average for 1850-1900.

Average June temperatures (°C) for Europe (top) and globally (bottom) from 1880 to 2019, shown as differences from long-term average values for 1850 to 1900. June 2019 is highlighted. Data sources: ERA5 (ECMWF, Copernicus Climate Change Service) and HadCRUT4 (Met Office Hadley Centre and Climatic Research Unit, University of East Anglia).

Spikes in European-average June temperature of more than 1°C above normal have occurred several times during the last 150 years; in 1901 and 1917, as well as 1999, for example. The temperature in June 2019 was exceptional because its spike came on top of a general rise of around 1.5°C or more in European temperature over the past one hundred years. This rise in European temperature is notably higher than that of around 1°C seen globally.