A rare natural phenomenon occurred in the early hours of Thursday morning, when the temperature shot up by more than six degrees Celsius in 20 minutes in a rare phenomenon called a 'heat burst'.

It was recorded in parts of Malta, but especially in Gozo, says Andrea Muscat who runs the Maltese Islands Weather website.

Muscat recorded data at his weather station in Għarb and has compiled a report to back up his theory. He has been collecting data since 2012 and believes it is only the fourth time the phenomenon has happened in the past eight years, normally around April or May.

Andrea Muscat recorded Thursday morning's 'heat burst'

"This time it started at 2.19am when the air temperature rose rapidly by 6.1°C (from 20.6°C to 26.7°C) in a space of just 20 minutes. Levels of relative humidity also experienced a sharp drop, from a humid 80 percent to an extremely dry 37, all in a gap of just a few minutes."

But this unusual event doesn't just involve a change in the temperature, it also needs other very specific conditions.

"In typical heat burst fashion, the wind increased dramatically from a complete calm to 40.2 km/h (Force 6)," says the 24-year-old from Gharb.

"The behaviour of air pressure also reveals tell-tale signs of a heat burst. It climbed by 2hPa, from 1009.5hPa to 1011.5hPa, which - in layman's terms - means the weight of the air above the ground changed dramatically. A heat burst has been likened to someone blowing down on a puddle of water."

Visual explanation of a 'heat source' SOURCE: Wikiwand

Muscat said he had received reports of many people, especially those residing in Gozo who felt the heat burst and turned on their cooling systems. The effects were felt less the further south you went across the islands.

Muscat - who studied meteorology in The Netherlands - says the natural occurrence happens mainly in warms seas, but colder places like the UK have also recorded similar weather events.

Thursday morning's heat burst most probably can be blamed on a cut-off low pressure system, which traversed the central Mediterranean during the night between Wednesday and Thursday. This cut-off low had several embedded isolated thunderstorms within it. Most were in an advanced stage of dissipation. One of these isolated thunderstorms passing just off Gozo’s west coast is the likely culprit, he explained.

Data from Gharb weather station recorded on Thursday morning

And digging a little deeper into the science he explains: As a thunderstorm starts to dissipate, its clouds rise, leaving a layer of cold air beneath. At this stage, much of the moisture has been eliminated from the air by earlier precipitation.

Due to gravity and disappearing updrafts (currents of rising air within clouds), the dense air starts to sink to the ground. As its descent accelerates down, the air is subjected to increasing air pressure and friction. The increased atmospheric pressure causes the air to warm under compression. The friction between falling and stationary air particles creates additional heat.

The result is a heated, dry pocket of air that hits the surface, forcing warm gusty wind to disperse away from this point of impact.