since us “babyboomers” invented climate change may to mid august, the”dry”,july would be the best month,june is ok early august as well but in 2022 last 2 weeks of august got hot quick.South easterlies blow dry season but its flakey if your planing on sailing carry extra fuel,if a power boat the SE breeze depending on velocity can stir up the seas by 10-1100hrs and make it unpleasant.The daytime temp eases during the dry and it is made more pleasant by the SE breeze but be aware that the temps of recent “drys” get to low to mid 30’s requiring sun protection.The nights cool off june/july nights are “cold” to locals but have the bonus of keeping mosies/sandflies subdued.BTW if you don’t have it already download a copy (free) of Freemantle Sailing Club Cruising Guide.
cheers steve

I agree with Steve. April – May is usually the strongest and most persistent southeasterlies. They start to drop off a little in June, when the north and northwest afternoon sea breezes start up with some consistency. You can just about rely on getting several days in a row of calm weather from July to Sept. But you can also get days on end of 25 knot easterlies. First week in Sept is usually my time to turn around and head to the air-conditioning in Darwin, as it starts to get hot and muggy.

If you want to see the creeks and waterfalls running, you need to be out there as early as possible in the season. They start to dry up late May/June and can often be down to a trickle by late June.

Cheers Ross