Originally Posted by Seltzer

You could use Excel VBA to write a macro to do it, rather than 'visually' recording a macro - e.g. if you click edit for the macro you've created already, Excel will show you the VBA code behind it.

Basically you want an expression that will calculate the averages of the cell ranges B2 + 288i : B288 + 288i and output them to cells E2 + i, where 24*12 = 288 is the offset of cells from time x at one day to time x on the next day, and i is a number which starts at 0 and increments until it reaches 90.

This can be achieved in programmer terms by using a FOR loop. Unfortunately I've never used Excel VBA so I don't know the syntax that you would use to create a for loop, select ranges of cells, use Excel functions, alter cells etc. so I can only steer you in the right direction. I've got loads of assignments atm, but if you can wait until later today, I could learn a bit of VBA and figure out how to do it.