What happens in markets in the first 10 months of the year can shed light on what might happen in November and December.

The statistic-minded folks at Bespoke Investment Group crunched some numbers going back more than a century and came up with this interesting tidbit – when the Dow Jones Industrial Average is up 10 percent or more through October, the next two months have yielded positive Dow returns 87 percent of the time.

2009 marks the 47th time since 1901 that the Dow has topped 10 percent through October. When that occurs, Bespoke says, there has been an average Dow gain of 4.2 percent and a median gain of 3.6 percent through the end of the year.

Here's another factoid – regardless of performance through October, the Dow has averaged a 65-basis-point gain in November over the past century. The results are better over the past 50 years and 20 years – monthly gains of 1.21 percent and 1.79 percent, respectively.

You can see in the yellow bar on the chart above that November is the second-best month for the Dow (trailing only April) over the past 20 years, and the reddish bar shows that November and December are two of the best months over the past 50 years.

There are, of course, no assurances, that this year will follow the strong November-December historical trend. In 2007, for instance, the Dow dropped nearly 5 percent in the last two months of the year as the U.S. and other countries slipped into recession.

But for what it's worth, Bespoke says all of the other five November-Decembers with negative Dow performance came before the end of World War II (1912, 1918, 1919, 1925 and 1943)