Fires in brushland or scrubland. Credit: georgeburba

Devastating fires in parts of the Mediterranean during unprecedented heatwave

19 July 2023 00:00-26 July 23:59 UTC

Fires in brushland or scrubland. Credit: georgeburba
Fires in brushland or scrubland. Credit: georgeburba

After two weeks of dry and very hot weather in parts of the Mediterranean, several countries have been impacted by devastating wildfires.

Last Updated

27 July 2023

Published on

27 July 2023

By Djordje Gencic, Ivan Smiljanic, HansPeter Roesli and Jochen Kerkmann

A massive and stagnant dome of very warm and dry air dominated the weather from 10 July, across parts of southeastern Europe and much of the Mediterranean, caused by a seasonal strengthening of the ridge of the Azorean high pressure system (Figure 1).

Meteosat-11 SEVIRI Airmass RGB with ECMWF 500 hPa Geopotential, 20 July 12:00 UTC
Figure 1: Meteosat-11 SEVIRI Airmass RGB with ECMWF 500hPa Geopotential, 20 July 12:00 UTC

However, this year's case is extreme due to the absence of weather systems that would, at least for a brief period of time, break that dominance by pushing cold fronts through the region, bringing some relief. Very dry, hot, and occasionally windy conditions, prevailed over the course of two weeks and caused a very high risk of wildfires in many areas in Mediterranean.


Devastating fires impacted islands of Rhodes, Corfu, as well across mainland in Attica and Peloponnese.

The first large fire in the period in Greece, was in western Attica peninsula on 19 July, which was quickly extinguished, but managed to burn a considerably large area due to conditions being very conducive. Figure 2 is the Sentinel-2 L2A True Colour RGB, which shows a huge contrast between green and burnt vegetation, plus smoke from the active fires.

Sentinel-2 L2A True Colour RGB over west Attica, 19 July
Figure 2: Sentinel-2 L2A True Colour RGB over west Attica, 19 July

The most fierce wildfire was in Rhodes where almost 15 percent of the island had been burnt by 26 July. Rhodes lies in the part of the Aegean Sea heavily affected by the seasonal northerly wind circulation related to strong overheating of the Asia minor and Middle East — wind is one of the main contributors to the spreading of wildfires. This can be seen in the Meteosat-11 Natural Colour RGB with wind barbs overlaid (Figure 3).

Meteosat-11 SEVIRI Natural Colour RGB with ECMWF 925 hPa wind barbs, 22 July 12:00 UTC
Figure 3: Meteosat-11 SEVIRI Natural Colour RGB with ECMWF 925hPa wind barbs, 22 July 12:00 UTC

Here one can see a pattern typical for summer months — wind from northern quadrants. Additionally, due to the sensitivity of VIS0.6µm (blue component of the RGB), a smoke plume appears in light blue, especially visible over the sea.

Massive fire in Rhodes can be seen in IR3.9µm loop (Figure 4). Fires are seen as hot spots in the imagery and in greyscale view they appear completely black. Saturation of the IR3.9 happens at 336K and fires above that temperature typically show as an artefact in shape of concentric circles, as it can be particularly seen on 22 July when this pattern covers much of the island, reflecting the strength of the fire.

Figure 4:  Meteosat-10 SEVIRI IR3.9, 20 July 07:15UTC-25 July 07:15UTC

Fires and smoke are particularly visible during the day, and in composites that use the visible part of the spectrum. One of the ways to ensure a 24 hour view of the fires, is to use the Night Microphysics RGB, which features the crucial IR3.9µm channel. Although primarily used for fog/low cloud detection, it also can be used for tracking fires, as it can be seen in Figure 5.

Figure 5: Meteosat-11 SEVIRI Night Microphysics RGB, 17 July 18:30 UTC-23 July 18:30 UTC

Figure 6 shows a loop of three individual Sentinel-3 SLSTR scans of Rhodes, during the most intensive phase of the fire (22-24 July).

Sentinel-3 SLSTR Natural Colour RGB, 22-24 July
Figure 6: Sentinel-3 SLSTR Natural Colour RGB, 22-24 July

The Natural Colour RGB detects the smoke thanks to VIS0.6µm, and also shows the active fires in the area that already had been burnt. Active fire appears as red/bright red, due to the dominant signal in red component (NIR1.6µm) ,while the burnt area (also called 'burn scar') shows as different shades of brown. This brown colour comes primarily from the absence of chlorophyll (all vegetation burned), which strongly influences the green component of the RGB (VIS0.8µm). In this case the area is still quite hot, and, therefore, this colour comes from a moderate red and decreased green contribution (compared to area with vegetation).

The Natural Colour RGB from Sentinel-2 L2A (Figure 7), zooms in on a scene of fire in Rhodes, where unburnt vegetation shows as green and burnt in brown, active fires in bright red, and, finally, thanks to VIS0.6µm component smoke as a light blue, almost transparent, veil above the area.

Sentinel-2 Rhodes L2A Natural Colour RGB, 19 July
Figure 7: Sentinel-2 Rhodes L2A Natural Colour RGB, 19 July

Figure 8 shows experimental 2.5min FCI rapid scan commissioning data for southern Greece, in the form of the True Colour RGB combined with signal from 3.8 and 2.2 micron channels, in the regions with fires. It highlights the improvement in temporal (2.5 min), spatial (0.5-2km), and spectral resolution (presence of 0.4 and 0.5µm channels), to the previous generation of GEO satellites. Active fires show bright red-yellow-white, and smoke in brown or grey.

Figure 8: MTG FCI True Colour RGB, 22 July 10:00-16:30 UTC. Note: This is not operational data


On the Mediterranean coast of Algeria on 24 July, there was an outbreak of strong wildfires, under the aforementioned weather conditions. In the colour enhanced IR3.9µm loop for 24 July (Figure 9), shows the fires as hot spots appearing in many places over the course of the day.

Figure 9: Meteosat-10 SEVIRI IR3.9, 24 July 00:00-23:59 UTC

Figure 10 is the Natural Colour RGB loop for the same period.

Figure 10: Meteosat-11 SEVIRI Natural Colour RGB, 23 July 00:30 UTC-25 July 12:30 UTC


At approximately same time, there was an outbreak of fires across Sicily, following two weeks of dry and hot weather.  In the Meteosat-10 Enhanced IR3.9µm loop (Figure 11), the highest temperatures are coloured in yellow and red, indicating the fire tempearture. One can see that fires were increasing in number on 24 July and, especially, on 25 July, affecting significant parts of the region.

Figure 11: Meteosat-10 SEVIRI IR3.9, 24 July 00:00 UTC-26 July 23:59 UTC

Our deepest sympathies are with those impacted by these events.