daily averages of hourly data

Hi

I have some data with hourly averages. I would like to find the daily average in the next column.

I've uploaded an example file.

In column G in the uploaded file I would like to list each date once, and then in column H the 24 hour average from the date shown in G.

I'm thinking this can be a two step formula - so first the date and then in column H a new formula using =averageifs(...), taking the average if the date meets the criteria. Not sure this is the smartest way to do it though.

Note that some of the measurements are #NA. This is not a mistake.

Unfortunately using VBA is not really an option. This has to be done by formulas. Any help is very much appreciated,
Kbka