I saw this on somebody's blog,
"Historically, September and October are the two worst months for stocks in the US. Some of the biggest declines occurred around this time of the year. They include the crashes of 1929,1966,1973,1987 and 2008 (vividly etched on our minds)."
Earlier, I predicted that the stock market will rise for the month of September. I am not trying to defend my forecast. Rather, things tend to be the case until they do not occur. After which, we call it a surprise. The same applies for "sell in May and go away".
For those who want to know more of related predictions, you will find that most military coups in Thailand occur in October and November. Then of course there are years when they do not.