Nate Silver's The Signal And The Noise has a chapter about this. The short answer is yes,, weather forcasting has gotten better, but comerical forcasts have a known "wet bias" in favor of predicting rain. The reason for this is that people get more upset at forcasters when they say it won't rain and it does than when they say it will rain and it doesn't. Acording to Silver, the National Weather Service's forcasts are the most reliable, followed by various large comercial services (e.g. weather.com. etc.), with local news forcasts being the least reliable.