Why drought is your friend: 1
First of all, the drought kills weeds. Those soft, fleshy, water-hungry weeds soon wither and die when it gets really dry. On the other hand, you see how remnant dry rainforest species can withstand extreme dry conditions. The Calllistemons, Denhamia, Wonga Vines, Supplejacks, Brush Turpentine, Cryptocarya, Hard Quandong, Muttonwood, Brown Myrtle, and Smilax all are great drought tolerant species.
But that's not all. The dry can also help you kill weeds (if you are quick).
In dry conditions, a couple of days after showers, you can spray effectively with the minimum of herbicide, and thats got to be a good thing. The weeds are growing, responding to the water they just had, so they are extremely susceptible. That means you can use less. But don't leave it too long! Herbicide is virtually useless on drought-stressed plants, because they shut down.
Some weed species of course, like Asparagus Fern, Ochna, Mother of Millions, Mother-in-law Tongue are drought resistant, which leads us to reason number 2.
Why the drought is your friend: 2
In extremly dry conditions, you can keep your local native species alive without watering. How? By weeding!
Weeds like Ochna, Asparagus Fern, Chinese Elm, Privet, Balloon Vine, Cats Claw and Camphor Laurel all take massive amounts of water out of the system.
Asparagus Fern in particular is a water hog. Its crown and its network of surface roots sucks up the slightest shower before it gets to any nearby natives. And any sub-soil moisture is feeding the weeds first, because they are growing so aggressively.
If you slice the crown off a large Asparagus Fern and dribble some neat herbicide onto it, you will see nearby remnant native species pick up as if by magic. If you have a reasonably heavy infestation of weeds, your efforts will be a hundred times more effective in the drought than they would be in better conditions.
Why the drought is your friend: 3
Thirdly, the drought shows us where to plant and gives us access to these planting areas.
The drought forces the weeds to retreat to the moist riparian (creek edge) areas. So anywhere you can see a healthy crop of weedy Sedges, Ruellia, Wild Taro, Billygoat Weed, Flannel Weed, Nightshades, and other fast growing water lovers -- that's your target. You won't get a better opportunity to replace these weeds with thickly planted Carex, Juncus, Lomandra, Casurinas, Waterhousea, Blackbean, Silky oak, Bangalow palm, Cheese tree, Backhousea and Callistemon.
The drought does half your weeding for you and makes weeding easy. They lift out of the moist areas with hardly any effort, and leave a hole for lomandras and the like.
So there's three reasons why the drought is your friend. It's all about working with nature, not fighting her. If you try to fight, she wins. If you work with her, you both win.