I reckon this humid weather is becoming more common WV. In a couple more decades
this could be the normal in Melbourne. Climate change?
Yep. The highs are moving south as the upper troposphere becomes more stable (and baroclinic instability declines), while ocean temperatures are rising.This combination means more easterly weather and higher humidity for us.
About 10 years ago I led a study for engineers which looked at what was happening with extreme humidity, and as you'd expect it was rising with ocean temperatures (the high dewpoints had risen by about 1C, so about 7% more moisture). This type of study then feeds directly into dam spillway design etc so is taken seriously (i.e., you have to be very careful with your data and analysis methods). Just a single case but last December we set a record high dew point for Victoria. I like the humidity, but appreciate many don't.
Progs showing now break in the pattern with GFS and EC going for a major repeat of the thundery weather from around Tuesday or Wednesday.