I've been looking around for ideas to keep cool when you could fry
eggs on the footpath outside. Heres some of the ideas we tried:

1. Pin up a bed sheet or blankets outside your windows. The key is to
do it outside rather than inside - you want to stop the heat before it
enters the your house - not afterwards. Also try to leave a gap
between the barrier (sheet, blanket etc) and the wall or glass of your
home - that way you'll get less heat transfer. Here's a guy who used
$5 reflective blankets to keep his home cool (just make sure you don't
position the blanket so that it bounces the heat somewhere you don't
want it - you might end up frying your garden).

2. Put a wet blanket over the top of the car and cover all the windows
(this didn't harm my duco at all - but try it at your own risk).

3. Cut the bottoms off water bottles, dig them neck down in the soil
beside sensitive plants and fill with water - this should drain into
the soil gradually throughout the day. You can cover plants likely to
burn with bed sheets too - pick a light colour to reflect heat. Of
course you can always take the attitude of my friend Tim, and see days
like Friday as a form of natural selection - let the heat kill of the
tender ones, and replace them with some tougher plants.

and the best one of all...

4. Run away. Go stay in a 5 star hotel with a pool and air con. We did
this on Friday night, and it was fantastic. I figure that the hotel is
cooling the whole building anyway - and for the 5-6 nights of the year
that are so ridiculously hot that good passive design and fans can't
cope - it's a better option than shelling out for an air conditioning
system which is just going to contribute to pushing up peak demand and
blackouts.