try PROC MEANS, which has at least two options that meet what you seek. Copied from the online-doc :
COMPLETETYPES
Create all possible combinations of class variable values
CLASSDATA=
Specify a secondary data set that contains the combinations of class variables to analyze
In that secondary data set you would place the time points at which you want summary.
Perhaps you should follow the examples
http://support.sas.com/onlinedoc/913/getDoc/en/proc.hlp/a000357025.htm
Another way to make PROC MEANS do what you need might be to use the "PRELOADFMT" feature described in the doccumentation and demonstrated at the example
http://support.sas.com/onlinedoc/913/getDoc/en/proc.hlp/a000353486.htm
just remember to use a format for the datetime value that gives you the hour of the day ( even if you have to create it ~~> with PROC FORMAT
😉
all good solutions
good luck
PeterC