All you want to do is change the ‘units’ used in the plots just like you would to plot temperature inC or F. In this case you need to tell WeeWX the units you wish to use for group_interval is hours not minutes. Unfortunately, that is done on a skin by skin basis and can’t be done on a plot by plot basis. Try adding the following (untested) to WeeWX.conf under [StdReport] [[Seasons]]:
[StdReport]
….
[[Seasons]]
….
[[[Units]]]
[[[[Groups]]]]
group_interval = hours
Save weewx.conf and restart WeeWX. This should cause all of your plots that include an observation that belongs to group_interval to plot in hours rather than minutes. You may need to delete plots with an aggregate period (eg week, month and year) to force them to be re-generated otherwise you will need to wait for them to re-generate.
This approach may have some unintended consequences in some reports or (possibly) other plots, unfortunately I am away from my PC and cannot test the change. If this does work and gives you (some of) the plots you want you can achieve a plot by plot effect by create a cutdown copy of the Seasons skin that will just produce the plots in hours (and nothing else) and the original Seasons skin can produce everything else plus your plot in minutes.
Gary