Leading the way is the Nasdaq composite, which averages a 2.1 percent gain for the month, and has posted a positive return in six of the last 10 years. The S&P 500 averaged a 1.6 percent rise and has also been positive in six of the last 10 years.
The crown for batting average, however, goes to the Dow Jones industrial average, which has posted a positive July return in seven of the last 10 years. The average gain during that time span was 1.9 percent.
Read MoreStocks in the first half offer a very mixed bag
The broader market strength also plays out in all 10 sectors of the S&P 500 index. During the last decade, the month of July has led to average gains across all of them. Some fare better than others.
Oil prices appear to have stabilized for the time being, and that may help energy stocks continue their bullish July trend. The sector has posted positive returns in eight of the last 10 years, and the average gain was 1.4 percent.
Technology, the largest sector of the S&P 500, posts a more impressive 2.4 percent average gain, but has been positive in seven of the last 10 years. Meanwhile utility stocks post the smallest average gain for July on average, at 0.5 percent, and have been positive in six of the last 10 years. Materials stocks have turned in a negative performance more often not over that time span.