Formation of thick cirrus clouds due to a decaying front passing over the Maltese Islands which was not shown in the actual surface weather chart. Sometimes they obscured the sun completely. Although the cloud was moving in from a westerly direction, they appeared as an irregular patchy pattern (proven in the first photo thumbnail taken up to 30 minutes later) hence the weather remained fair for the following hours and days. The front itself was decaying because it was moving into the zone of high pressure.