Hi Kia Orana,
The southeasterlies start to drop off around October, and the later you leave it after September, the less chance of strong southeasterlies. From late November, you might even be lucky enough to get a norwesterly breeze. I’ve crossed W to E 7 times between late Sept and Dec and I’ve yet to see any sign of a breeze from anywhere near the west. People tell they do exist though.
My strategy is to sit in Gove and wait for a reasonable weather window to head across the Gulf. Anything under 20 knots for a few days is reasonable to me. Dont try it in anything from the east over 25 knots – you won’t enjoy it!
You need to consider cyclones in December. Although unusual to get a cyclone in December, it is possible. If you’re still in FNQ in Dec, keep a close watch on the weather and consult “Cruising the Coral Coast” for the nearest bolt hole if you see a cyclone forming.
The toughest part of the trip can be down the Queensland coast from Cape York to Cairns, where you’re just about guaranteed to get southeasterlies. Be prepared to spend a few days into 15 – 25 knots on the nose. If you’re a power boat, staying close to, and in the lee of the reef can significantly reduce the short, steep seas in this area. If you’re sailing, you’ve got lots of tacking to look forward to.
Have a great trip,
Ross