Satellite before and after

Quebec wildfires 2023: burn scars in the boreal forest

Canada's 2023 wildfire season was the largest on record. In Quebec more than 150 fires, some started by lightning, were already burning by early June.

Boreal forest of central Quebec, south-west of Lake Mistassini, Canada · June to September 2023 · Wildfire · Canada

Compare the imagery

Drag the divider, or focus it and use the arrow keys. Left of the divider is 28 May 2023, right is 5 Sep 2023, 100 days apart.

The interactive comparison needs JavaScript. Both images are shown below.

In this false-colour view water is dark blue to black, vegetation is bright green, bare ground is tan, freshly burned land is red-brown and cloud is cyan.

The two images

Satellite image of Boreal forest of central Quebec, south-west of Lake Mistassini, Canada on 28 May 2023, before the event, in false colour (MODIS bands 7-2-1).
Before: Terra, 28 May 2023 · Open in NASA Worldview · original from GIBS
Satellite image of Boreal forest of central Quebec, south-west of Lake Mistassini, Canada on 5 Sep 2023, after the event, in false colour (MODIS bands 7-2-1).
After: Terra, 5 Sep 2023 · Open in NASA Worldview · original from GIBS

What the images show

On 28 May the forest is unbroken dark green, set with lakes. On 5 September red-brown burn scars are scattered across it, several of them tens of kilometres across.

About the event

  • NASA Earth Observatory reported that by early June 2023 about 160,000 hectares had burned in Quebec that year, where in an average year only 247 hectares would have burned by 5 June.
  • By October it reported an estimated 18.4 million hectares burned across Canada in 2023.

Limits of this comparison

Both images are from the same satellite and layer, 100 days apart, so the scars are from many separate fires. Some cloud covers the north-west corner on 5 September.

Each image is one satellite pass at about 250 metres a pixel. It shows where water or burned land is visible from space on that day; it does not measure damage, and cloud or haze can hide what is underneath.

Dates were chosen by checking the imagery on both satellites for several days either side and keeping the clearest pass. Both use the same layer, MODIS Corrected Reflectance, bands 7-2-1.

Sources

We acknowledge the use of imagery provided by services from NASA's Global Imagery Browse Services (GIBS), part of NASA's Earth Science Data and Information System (ESDIS). Comparison slider: leaflet-side-by-side (MIT licence). Case last updated 13 Sep 2026.

Questions

What does the satellite image of Boreal forest of central Quebec, south-west of Lake Mistassini, Canada show?

On 28 May the forest is unbroken dark green, set with lakes. On 5 September red-brown burn scars are scattered across it, several of them tens of kilometres across.

When were the two satellite images taken?

The before-image was taken by Terra, 28 May 2023 and the after-image by Terra, 5 Sep 2023, 100 days apart.

What can this before-and-after comparison not show?

Both images are from the same satellite and layer, 100 days apart, so the scars are from many separate fires. Some cloud covers the north-west corner on 5 September. Each image is one satellite pass at about 250 metres a pixel. It shows where water or burned land is visible from space on that day; it does not measure damage, and cloud or haze can hide what is underneath.

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