This weekend will test our gardens. If you don't have tank, ground or recycled water, a few strategic buckets of water would be in order to keep susceptible plants alive until the Sunday watering. In the Royal Botanic Gardens in Sydney we've had a few trees wilt and some browning of leaves - saved to some degree by a sprinkle of rain on Australia Day evening, and by some extra watering by staff and Friends' volunteers.
At Mount Tomah Botanic Garden we are already rationing our water (from the dam and rainwater tanks), and if there is no rain in the next month or so we may have to truck in extra water. Some deciduous trees are colouring up and will undoubtedly lose some leaves, as has happened in Melbourne over the last few weeks (deciduousness - see posting below - is all about not supporting and exposing your leaves during tough times when there is little growth).
In Sydney we should expect burning of leaves and some leaf drop over the weekend. If the heat does kill parts of your plant, it's generally best to leave them there until all threat of hot weather has passed - why expose new leaves to the same burning?