The Hot Autumn (autunno caldo in Italian) of 1969–1970 was a massive series of strikes in the factories and industrial centers of Northern Italy, during which workers demanded better pay and better conditions. Between 1969-1970 there were over 440 million hours of strikes alone. The decrease in flow of labour migration from the South had resulted in nearly full employment levels in the North, meaning that the previously under-paid and unhappy workforce started to flex its muscles.
Due to increased literacy levels and student discontent, students started agitating for reform and increased class consciousness. Workers joined in on this, and began to demand better pay. Many of them were being laid off because of increased efficiencies in factories. Higher class consciousness was not achieved, but more basic demands such as a 40 hour work week, and increased pay were. [1]
The reasons for discontent varied - while the usual pay and conditions were a factor, it's fair to say that tensions were increased by the fact that much of the workforce had migrated from the much poorer south. They were generally unhappy at the society that had forced them to leave their homes in search of work and wanted to get back at the employers that had exploited the low average wages for so many years.
The phrase "hot autumn" has since been applied in the Italian press to describe other autumns with significant amounts of strikes. In the later years, such season strikes have more often been directed against the government's budget.
Similar periods in other countries around the same time:
Italy Hot Autumn Photo Gallery
Italy 60s-70s collection at the Libertarian Communist Library