Another Friday the 13th has arrived, the third and last one this year. Did you know that exactly 13 weeks ago was a Friday, April 13? And that exactly 13 weeks before that was a Friday, January 13? The fact is that any leap year starting with a Sunday will have a Friday the 13th in January, April and July.
Three Friday the 13ths also happen in any non-leap year that starts on a Thursday. In that case, the Friday the 13ths come in February, March and November.
The year 2009 was the last time we had three non-leap-year Friday the 13ths. The next time will be the year 2015. Notice each of those years is three years before and after 2012.