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.
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.