According to the Stock Trader's Almanac, the end of January signals the end of the best three months of the year for stocks. The average gain for the Nasdaq since January, 1971 is 3.7%.
For the S&P 500, the probability of an up day today is about 67%, but tomorrow is historically one of the best trading days of the year with the probability of an up day at 81%.
It also happens to be the day of the FOMC meeting.
Bernanke's coming, look busy.