1. Does your worksheet have any headings for dates or for hours.
2. You want the 365 columns converted into three columns.
At what date/hour do the first two columns stop, i.e what are the transition points and is there any logic to where those transition points occur.
I don't know how you intend to use your data, but moving from a logical array of 365*24 to three columns which 'mix' dates and hours, will make data analysis a lot harder.
Imaging trying to get an average value for 10:00 AM for the year
In your current arrangement you would use a simple formula such as =AVERAGE(A10:NA10),
but with the data split into three columns, It would require a complex formula to get the same result.
You could consider putting each month's data onto a separate worksheet in the same workbook, if for instance you needed compatibility with Excel 2003 (only 256 columns available).