CAMBRIDGE – Among the visitors to the 2009 Head of the Charles regatta was a somewhat unwelcome guest ? the New England weather.Even when it wasn’t raining, snowing, or both, the always-unpredictable weather conditions made their presence felt during the two-day regatta, now in its 45th year, on the banks of the Charles River Saturday and Sunday.Weathermen forecast a gloomy day on Saturday, and while crowds of people still turned out to watch the boats race past the upperclass dorms at Harvard University, the numbers in attendance seemed smaller than in previous years.Nevertheless, many people seemed to enjoy themselves on Saturday, sampling Philly cheesesteak and roast-beef sandwiches from vendors, examining the many items of regatta-themed clothing on sale, and taking free samples of products ranging from ice cream to vitamins.There were also races to watch, of course, and on Saturday afternoon, spectators lined up along one stretch of the 3-mile course – the Weeks Footbridge – to do just that. Others sat on the riverbanks, with a lucky few finding benches to sit on. Cambridge School Committee candidate Alice Turkel chatted up locals in advance of Election Day, and the police made things a little easier for pedestrians by closing off Memorial Drive to traffic.One thousand boats competed on Saturday, with Sunday drawing 880. In all, the regatta attracted over 8,500 rowers.