Do the hourly forecasts show an average over 3 hours or an instantaneous snapshot at an exact time?

[jonohewitt]

I've realised that I haven't really understood which data the hourly array in the json reports are showing. Are the values supposed to be:

a) representative of an average weather across a three hour period, e.g when time: 0, the data shows an average tempC between 00:00 and 03:00,

or b) an instantaneous report at that exact time, e.g at exactly 00:00 it will be this tempC.

I'm trying to understand whether it would be more accurate at, for example, 02:30, to show the time: 0 hourly data (option a) or the time: 300 hourly data (option b).

Thanks very much