I need to compute the average temperature per week for multiple years of data with 48 data points per day. How do I get the average temp per week.

An example of the data available follows.

Date and Time (EDT) Temperature (°F)
2012-06-26 16:01:37 84.2
2012-06-26 16:31:37 84.02
2012-06-26 17:01:37 84.74
2012-06-26 17:31:37 84.92
2012-06-26 18:01:37 85.1
2012-06-26 18:31:37 84.92
2012-06-26 19:01:37 84.74
2012-06-26 19:31:37 84.74
2012-06-26 20:01:37 84.38
2012-06-26 20:31:37 84.2
2012-06-26 21:01:37 83.48
2012-06-26 21:31:37 82.58
2012-06-26 22:01:37 82.22
2012-06-26 22:31:37 82.04
2012-06-26 23:01:37 81.86
2012-06-26 23:31:37 81.5
2012-06-27 00:01:37 81.14
2012-06-27 00:31:37 80.6
2012-06-27 01:01:37 80.24
2012-06-27 01:31:37 79.7
2012-06-27 02:01:37 79.34
2012-06-27 02:31:37 78.8
2012-06-27 03:01:37 78.44
2012-06-27 03:31:37 78.08
2012-06-27 04:01:37 77.54
2012-06-27 04:31:37 77.18