it's the mean for a particular month. My point is that there factors that can impact the whole of a month so comparing individual monthly means isn't necessarily conclusive. As you will well know the Wet Season in FNQ doesn't arrive on a particular date or even in a particular month. Cyclones & King Tides can massively distort a mean for a month etc etc.
I posted how sea levels are actually measured, by NASA using a satellite not using Australian BOM gauges. Why are you not looking at the NASA information?