Well, Ugadi is a South-Indian festival very unique of the other national festivals, wherein we, the Kannadigas, Tamilians and other South Indians feel, that this, the festival of Mango - Neem (Maavu-Bevu) marks the beginning of a new year unlike the English new year which starts Jan 1.
On this day, people usually bring out the latest edition of what is called a "Panchaanga", the Indian or rather the South-Indian year-book, April-March. This can also be called the Sanskrit counterpart of the English Calendar.
People refer to this for any eclipses that may occur during the year. Of course, any extention in a particular season. For example sometimes maybe rainy season will last a week or so longer we come to know in the Panchaanga. Also, this is not a scientific output. No science and technology is involved in preparing this yearly book. It is purely Sanskrit and Astrology.
Finally, after all these, People eat a bite of mango and neem both as a significance that lfe in the year have an equal balance of both profit (Neem-bitter) and loss (Mango-sweet). So that's Ugadi - The New Year for you. Happy Ugadi 2005.