Emily was born in late November and we live in Brisbane. Our upstairs area isn't airconditioned....swaddling was just not an option. It was FAR too hot. Luckily Emily slept very well and didn't mind just being layed in her cot.
As she got older (about 4 months or so) it started getting colder and she was rolling around the cot so we put her in a growbag. It worked really well, I never had to worry about her getting cold. They're great.