Here are 2 pieces that might help:

1. Insert a New Column with Quarter (Col B)
Created from Week date: ="Q"&ROUNDUP(A2/13,0)
Created from Calender date: ="Q"&ROUND(MONTH(A2)/3,0)

2. Where col B is Q1, Sum every row in col C:
=SUMIF(B1:B52,"=Q1",C1:C52)

Ola Sandstrom


Note:
Quarter from weekdate will not entierly correct, as Jim points out.
Quarter from calendar date will be correct.