Array Formula required

Hi guys

I have attached a spreadsheet of data that I would like to reduce.

In the workbook there is a set of data (rows 1 - 24) which are defined with random dates (row 2) and number criteria column A.

In the table below that (rows 28 to 37) I have set out how I would like to present the data.

So the question is; how to create an array formula that sums the above data months into the criteria of column A.

if there is any help out there please point me in the right direction

Cheers