French and Spanish firefighters face a critical few days in their battle against wildfires with the “intensity of several atomic bombs” as temperatures across the continent are set to rise to up to 40°C this week.

Authorities in both countries are calling on support from across Europe to tackle the devastating blazes that have forced hundreds of thousands of people to flee their homes, with emergency services braced for soaring temperatures and high winds in regions already engulfed by flames.

Satellite imagery and mapping of wildfire hotspots on Monday show the scale of the challenge facing governments and responders as the fires spread further.

Spain’s interior minister, Fernando Grande-Marlaska, said the next couple of days will be “decisive” as fire crews battle to hold back the flames from both the ground and the air, and as residents and tourists continue to be evacuated.

In the region around the city of Bordeaux, extraordinary atmospheric conditions have generated giant “fire clouds” that are intensifying the devastating fires and are now threatening some of France’s key strategic military and scientific bases. French President Emmanuel Macron convened a crisis cabinet meeting on Monday morning.