Sun shining through a dried leaf

European heatwaves in summer 2019

June and July 2019

Sun shining through a dried leaf
Sun shining through a dried leaf

Maximum temperature records were broken in many parts of Europe in June and July 2019, due to a series of heatwaves.

Last Updated

12 April 2022

Published on

01 June 2019

By Ivan Smiljanic (SCISYS), Sancha Lancaster (Pactum), Carla Barroso and Isabel Trigo (IPMA ), Andreas Salentinig (TU Wien ), Jose Prieto (EUMETSAT)

Summer 2019 in Europe echoed the summer of 2018 with periods of extremely high temperatures across Europe. Many places in Central and Western Europe saw maximum temperatures tumble more than once. The extreme temperatures started in June and returned in July.

The Evolution RGB (Figure 1) indicates thermal change (compared with uniform summer temperatures) in three periods. The colours show when 10.8 µm brightness temperatures are moderate. Blue is used to indicate normal values in the period from 24–30 June, green indicates normal values in the period from 1–18 July, and red indicates normal values in the period 19–28 July. These periods roughly correspond to the June heatwave, the interim cooler period and the July heatwave affecting western Europe in summer 2019. The limits of these periods were chosen subjectively.

 Brightness Temperature Evolution RGB, 24 June-28 July, daily at 13:45 UTC
Figure 1: Brightness Temperature Evolution RGB, 24 June-28 July, daily at 13:45 UTC

Unsurprisingly, green predominates in south western and Central Europe up to the Baltic Sea, where the maximum temperatures were the highest in the June and July waves. Ireland (red) was cooler at the end of July, whereas parts of Scandinavia (blue) were not affected by the first heatwave. Also the southern Alps and eastern areas (red) did not suffer the second wave, only the first. Over northern Africa, the source of the hot air, a colourful mosaic indicates in green the common part of the corridor for the two major waves.

Central Spain shows black, that is persistent heat throughout. Opposite to that is Greece, almost unscathed by the heat.

This RGB takes the highest brightness temperature in each of the periods noted above, based on the daily image at 13:45 UTC. The method does not completely eliminate cloud, therefore, the heat on the ground might be masked to some extent.

Figure 2 shows the different areas, in fact very similar, affected by both heatwaves. It shows the maximum brightness temperatures (BT) achieved at different Meteosat-11 pixels on channel 10.8 µm, in colours for the range 30–55 °C. BT is a proxy for ground temperature, normally some degrees above the air temperature at 2 m height, which is more representative of the thermal experience.

Maximum values of 10.8 µm brightness temperatures

Second wave, 18-28 July compare1
compare2
 

Figure 2: Comparison of Meteosat-11 BT RGB showing the two heatwaves in June and July 2019

Before and after comparison

Image from 27 July compare1
compare2
 

Figure 3: Meteosat-11 Natural Colour RGB 17 and 27 July, 09:00 UTC