Converting half hourly data to hourly data

Hi all

I have some data recorded at 30-minute intervals and I would like to convert to hourly values. The raw data is contained in columns A, B and C in the attachment. The output should take the form indicated in columns G, H and I where column H contains hourly total Radiation and column I contains hourly average Temperature. The dates in column G have been created manually but I need a way of doing it using the dates in column A. How do I use excel to get such an output?

Regards

Joe