When is the best time to visit the Australian outback?

The only time you'll find Central Australia in the low 30's or below is May to September. The rest of the year it'll be in the high 30's or the 40s. It's not impossible for it to hit the high 40's around Christmas time. And during that period it will also be cold at night - just above freezing most nights.

My parents have just done a very similar trip to yours, and they did it July to September, and that's when most people who are doing that kind of a trip will be doing it.

As for bushfires, there's very little out there to catch fire. Floods are very uncommon (but not impossible). I can only remember maybe two or three of them in the past 30 years. Drop bears live in tropical areas, so you'll be fine from them too.

A few asides: In the same way that many people remind tourists that the Autobahns are not a race track, I feel I should add some disclaimers here: You're proposing a dangerous trip. It's unlikely to end in serious consequences if you are prepared - but only if you are prepared. You can be 500 kilometers between fuel stops, a thousand kilometers from a hospital and 300 kilometers from the nearest mobile reception. Prepare wisely.

That said, I did this trip as a teenager with my parents in the early 00's, and my parents have just repeated it and had a wonderful time without major incident (apart from getting bogged on 5 mile beach and being rescued by a passer-by). And forget about climbing Uluru - that's no longer permitted and even when it was it was a political hot potato for as long as I can remember.

Weather wise, late winter/early spring is generally the best time to do this trip. Once you hit mid-spring daytime temperatures in the outback regularly get to 40C and above - Coober Pedy was 40 last Thursday (24th October). Officially bushfire season starts on November 1 but it is frequently brought forward and we have already had some fires this season. You can go earlier in the winter but be warned that in the desert overnight temperatures can drop below freezing. I actually did this trip (minus the detour to the Flinders) starting June 3 this year in a rented campervan and we frequently woke to ice over the windscreen, and if yours is anything like ours (an Apollo 4WD Adventure Camper) there is no insulation so you will need a good sleeping bag. The other advantage of traveling in spring is that if there have been any rains there can frequently be lots of beautiful wildflowers in the deserts. Flash flooding is highly unlikely on the route you're travelling but it would be most likely in later summer when tropical moisture can feed down from the north.

In terms of route, from Kings Canyon rather than backtracking to Erldunda to go to Alice Springs I would definitely recommend taking the Mereenie loop from Kings Canyon (Larapinta and Namatjira drives) as the scenery through the Western McDonnell ranges is spectacular and there's lots of good hiking and swimming holes. Some of this road is dirt but it's generally in pretty good condition although we did encounter one stretch that was pretty badly corrugated. Still, nothing a decent 4WD can't handle.

You will need to be careful driving at night (basically from the start of sunset to the end of sunrise) once you hit the outback and I would highly recommend avoiding it at all costs. There are a lot of stupid animals that love nothing more than to hop/run/wander out onto the road in front of your car, rarely giving you enough time to do anything other than say "Oh S..t!" before you hit them. If you must do it, slow down!

In terms of phone signal, as long as you get a Telstra SIM (or roam on the Telstra network) coverage is pretty good these days. There are gaps still, especially north of Coober Pedy, but not that bad (generally a couple of hours drive at most). There are plenty of fuel stops too, although you will get a bit of a shock compared to American prices.

As for dropbears, well, anywhere there's a tree, there's a risk.

Lots of good answers - a couple of extra notes.

• Your itinerary is great, but if you have the time I'd add "Mereenie Loop" to your Google Maps route between the Kings Canyon and Alice Springs entries. In my opinion there's lots more to see in the West MacDonnell Ranges than there is on the Stuart Highway north of the Ululru turn-off (except for Rainbow Valley...)

• As an alternative to the Western MacDonnells (or even in addition - it's only an hour or so south of Alice and worth the backtrack) Rainbow Valley is one of my favourite places - the road in is a bit rough but should be fine if you drive carefully. Make sure you camp there overnight - sunset and the stars over the rocks are awe-inspiring. There is no power or water, but definitely worth it. We camped there the last night of our trip and it was the icing on the cake!

• I thoroughly recommend http://traveloutbackaustralia.com/ - the advice is excellent and was extremely useful on my trip to the Red Centre in May this year.

Some cautionary tales

• You may think you're a big man that will be able to ignore the flies, but just buy a fly-net for your hat (you do have a hat?) when you see one on sale. You'll eventually crack and wonder why you waited.

• If you see fuel, top up. Fuel is VERY expensive, but its not worth doing range calculations to try and save money by waiting for a cheaper servo (gas station) down the road. Seeing the low-fuel light come on in the outback is stressful. Ask me how I know...

A couple of +1s

• Yes, come in May to September - with May OR September having better availability in campgrounds. We had great weather and good campsite availability in early May this year.
• All the roads on your itinerary have steady streams of traffic, so make sure you have sufficient fuel and water, STAY WITH YOUR VEHICLE, and help should be along soon.
• Yes, stay off the road between dusk and dawn. You'll almost certainly find a night-driving prohibition in your camper rental agreement anyway.
• Drop bears are a fact of life, so just buy a jar of Vegemite and smear some across your forehead to guarantee your safety. Aussies don't need to do this as the Vegemite is in our blood and comes out in our sweat, but visitor shouldn't take the risk.

While there are some very good animal jokes in here, I just want to reiterate that the points about roos and night driving are very much real. While they're lovely creatures and mostly(!) docile, they're also pretty stupid when it comes to judging distance and velocity. They seem to like jumping out in front of you. I counted 11 carcasses in the 128km from Toowoomba to Brisbane once and that's not even outback territory. There's also a lot of them. The question isn't if you'll see one, but how many dozens you'll see. I've personally collected a wallaby (about 1/4 the size of a big red or grey) which did 3K worth of damage to my car and that only hit the corner. A guy I work with hit one dead on with a 4WD with a bull bar and had to pry the thing out with his hands. My grandmother had a big red jump square on her hood when she was young and it wrote the car off. The roo was fine...

My point is, you really don't want to be driving after dusk. You're more likely to hit a roo than not out there and they'll make a bigger mess of you than you will of them.

Having said that, if you're over nighting in one of the smaller townships out there, go a few kms outside of town at night, get out of your car and look up. I promise you won't be disappointed, especially if you come from a large city.

I was recently at Alice Springs and Uluru, although we flew in and took bus tours.

The main thing to keep in mind is that it will be super hot. In december it was 47 degrees.

We were okay because we stayed in a 4 star hotel with air conditioning and swimming pool. Plus the tours we did started at 04:30 and ended before 10:00.

Personally I wouldnt do a campervan tour in the summer. Avoid December to April. Without air conditioning and a swimming pool you will honesly be very hot and uncomfortable.

Plan instead to go like the other answer says, between July and September.

Always be smart, take lots of water, spare fuel, make sure your spare tire is in good condition and that you know how to jack and change the wheels.

Be sun smart, use sun screen and insect repellant. And watch out for drop bears. They are vicious even outside of mating season.

Enjoy your trip!