It would be close to sugar cane harvesting season around now. Which would mean alot of burning prior to the harvesting of the cane. What you may have been seeing was high level smoke.
I was in Cairns late June and there are plenty of stars in the skies compared to my usual haunt in inner Sydney
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Good luck with the humidity if you do move up there. Brisbane was bad enough for me when I lived there 10 years or so ago.
Wayne