The July 2007 Argentine winter storm resulted from the interaction of an area of low pressure systems across central Argentina and the entry of a massive polar cold snap during the 6–8 July 2007; it was the worst winter of Argentina in almost forty years. Severe snowfalls and blizzards affected the country. In Patagonia, several lakes were frozen. The cold snap advanced from the south towards the central zone of the country during Friday, July 6, continuing its displacement towards the north during Saturday, July 7 and Sunday, July 8. On Monday July 9, the simultaneous presence of very cold air, above the average levels of the atmosphere as in the surface, gave place to the occurrence of snowfalls even in localities where snow is very rare. This phenomenon left at least 46 people dead in A