The mingling of hot air from southern Germany and air form the north, which was 10C cooler, created conditions that resulted in the violent storms which devastated parts of the state of North Rhine-Westphalia on Monday night and Tuesday morning.

Thomas Ruppert of the German Weather Service (DWD) said on Tuesday that the hot southern air brought high temperatures of 37 degrees. The country baked over the holiday weekend in record temperatures.

That hot air then met with cool northern air which had blown in over from the English Channel. Ruppert said normally nature tries to mediate the tension between these two temperature extremes but "eventually it snaps".

Once the hot and humid air had risen, thunderstorms formed and created strong gusts of wind. Wind speeds of over 140 km/h were measured, which, according to Rupert, is quite rare.

According to the DWD, an average of 20-40 thunderstorms hit Germany in a given place each year, typically in the summer. They usually bring heavy rains and occasional hale.

Around two million lightning flashes also occur in the country annually. However, only 200,000 to 400,000 of these touch the ground, according to the DWD. The majority travel from cloud to cloud.

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