Day lenght in realtime second

Hi, I making a script include weather, time, climate,etc. but that isn’t important. I want make my day length is 1, 2, 3… minute. Oh, and I want (enum) month change every 30 days, and year + 1 every 365 days (366 if it is leap year), show the month and year by GUI.Label (I don’t want the year show 2013.1624765, just show 2013)
And curTemp change every 1 day between MinTemp and MaxTemp.

If I would do this I would implement basic system and then use the player’s system time and time played to calculate my game time. Could probably do it another way but this is first thing to come to mind. Temperature even easier, just randomize every time your day variable increase.