Julie,
Before you hit someone else with sarcasm, think about how you come across.
If you have not done CPL or ATPL Meteorology, fair enough. If you have, then I'd dive back into your theory notes.
To answer.
The "Wet" pertains to the Wet Season in the northern part of Australia when the good ol' ITCZ shifts south bringing monsoonal conditions. Lots of rain, lots of thunderstorms and the occasional cyclone to spark things up.
Which month this happens is the talk of the locals "up north", but "Summer" is a reasonable answer.
Also, I punched in
"When is the wet season in Australia" into Google and got a few hits.
The flying rate overall is less than in the "Dry" because of fewer tourists. However, many communities are cut off because of rising flood waters or washed out roads. So, for the crews that remain during the Wet, they are still busy. It is more challenging and requires a bit more experience.