Is there a predefined enumeration for Month in the .NET library?

There isn’t, but if you want the name of a month you can use:

CultureInfo.CurrentCulture.DateTimeFormat.GetMonthName (DateTime.Now.Month);

which will return a string representation (of the current month, in this case). Note that GetMonth takes arguments from 1 to 13 – January is 1, 13 is a blank string.