Climatic history in Brazil: Snow & 'One of the coldest days ever witnessed in September'

From here (PDF):

Friday, September 5th 2008. This day will go in our climatic history of the southernmost state of Rio Grande do Sul as one of the coldest ever witnessed in September. It was an amazing day. Temperatures below 5 degrees Celsius during afternoon hours are quite rare even in the coldest months of calendar from June to August, but today temperature dropped to 2 degrees in several cities after midday with the lows occurring during the afternoon. ... MetSul’s chief meteorologist Eugenio Hackbart notes that it was for sure one of the coldest ever recorded afternoons in September in a century. Hackbart explained that the synoptic pattern that favored this Friday snowfall in Rio Grande do Sul (Brazil) was very similar to the one that produced the first snow in Buenos Aires since 1918 last year. The region was covered by a very cold air mass and a low pressure system advanced from North Argentina, bringing rain that converted to snow under the influence of the frigid polar air.

Meteorologist Eugenio Hackbart, a long time declared skeptic on manmade global warming, observed that extreme cold or snowfall events tend to occur during winter with negative PDO, solar minimum and La Niña. The most important snow events in Southern Brazil during the last 50 years, according to him, occurred at or around the 11- year cycle solar minimum. “Of course, it snow in year of heightened solar activity and El Niño, but history tells the most impressive episodes took place in winters either with La Niña or negative PDO in the Pacific or during periods of lowered solar activity”, he says. MetSul’s meteorologist also notes that the return of the colder winters and the major snow events to the area of the Southern Cone of South America may be the result of the ongoing cooling trends observed in the planet this decade. “This is no coincidence”, he says.