Australian summer can hit 45°C in the right (wrong) places. A Mars caravan handles it, but only if you set it up right. Here's how to stay comfortable, protect the van, and not destroy your batteries trying.

Site Selection — Half the Battle

• Shade beats aircon. Park under a tree (well clear of dead branches) or up against a building shadow if you can. A van in full sun on a 40°C day pulls ambient internal up to 50°C+ within an hour. Shade can cut that to 35°C without the aircon running.
• Orient the van. Park the long side facing south (less direct sun) or in the direction of the prevailing breeze.
• Avoid bitumen. Sealed surfaces re-radiate heat well into the evening. Grass and dirt are 5–10°C cooler around the van.
• Watch for cooling at night. Inland sites cool dramatically after dark; coastal sites stay warm and humid. Plan for the right kind of overnight.

Van Setup for Heat

Before You Park Up

• Open every roof hatch and window once you arrive to vent built-up heat.
• Pull blinds closed on the sun-facing side. Reflective blinds are far better than fabric ones.
• Run the awning out — it shades the awning wall and reduces solar gain through that side.

The Aircon Sequence

1. Vent first — open up briefly to dump trapped hot air (this is faster than asking aircon to cool 50°C air).
2. Close everything once vented.
3. Start the aircon on high fan, target temp 22–24°C.
4. Once you're close to target, drop to medium or auto fan.
5. Keep doors closed — every open of the door costs you 2–3°C.

Don't chase 18°C in 45°C heat. The unit will run constantly, your batteries will drain on inverter, and you won't actually get there. 24°C is comfortable and achievable.

Power Reality in Extreme Heat

Solar Production

Counter-intuitively, panels produce less when very hot — typically 10–15% less than at 25°C. Don't expect peak output in a heatwave.

Fridge Load

Fridges work much harder in 35°C+ ambient. The same fridge that uses 0.8 kWh/day in spring can use 1.5 kWh/day in 40°C heat. Plan for this.

Aircon On Inverter

If your van has inverter-capable aircon and you're off-grid, expect to drain batteries fast. A 2.5kW aircon on inverter pulls ~200A from 12V batteries while running. A 200Ah lithium bank gets you maybe an hour at full tilt. Use it in short bursts to dump heat, not continuously.

Smart Aircon Use Off-Grid

• Cool the van down in mid-afternoon when solar is producing — let the body of the van absorb the cool.
• Switch aircon off in the evening when temperatures drop.
• Use fans (ceiling, portable 12V) to keep air moving — much cheaper than aircon.

Sleeping in Hot Weather

• If you can wait until evening, open up the van and use cross-ventilation rather than aircon.
• A portable 12V fan over the bed is the single most useful piece of gear in summer — costs almost nothing to run and makes 30°C feel like 25°C.
• Damp sheet on the body works for evaporative cooling in dry inland heat.
• Coastal humidity is harder — aircon may be the only realistic option for sleep.

Protecting the Van From Heat Damage

Tyres

Hot bitumen + heavily loaded tyres = blowout risk. Check pressures cold, not hot. Don't drop pressures dramatically to "compensate" — pressure naturally rises with temperature; it's expected.

Fridge Vents

External fridge vents must stay clear in hot weather. Blocked vents → fridge can't dump heat → fridge fails to cool. Check and clean before extreme heat hits.

Sealants and Trim

Roof sealant, window seals and decals all suffer in extreme heat over time. Park in shade where possible to extend their life.

Gas Cylinders

Hot cylinders (in direct sun in the locker) build pressure. Modern caravan gas lockers are vented, but extreme heat (45°C+) for extended periods accelerates pigtail and seal wear. Park with the gas locker on the shaded side if possible.

Aircon Itself

Cleaning filters before a hot trip means the aircon doesn't have to fight a partially blocked filter on top of extreme load. 5-minute job; significant difference.

People & Pets — The Bit That Matters Most

• Never leave anyone in a van without aircon in 40°C+ heat. Internal temps climb past 60°C within an hour. Pets, kids, elderly relatives — never.
• Hydration: 3+ litres per adult per day in extreme heat. More if active.
• Heat exhaustion signs: heavy sweating, weakness, headache, nausea. Cool down, hydrate, rest.
• Heatstroke (medical emergency): hot dry skin, confusion, no sweating, fast pulse. Call 000, cool aggressively (water, fans, shade) while waiting.
• Watch the kids and the dogs — they don't always say when they're struggling.

Fire Danger

• Total Fire Ban days mean no open flames outside the van. That includes BBQs (unless gas BBQs are specifically allowed in your area on TFB days — check local rules), camp fires, and many forms of cooking.
• Check the fire danger rating before leaving and daily on trip.
• Have a plan — know two exit routes from any campsite in high fire risk areas.
• Don't camp in dense bush during catastrophic fire danger periods.

The Gear Worth Carrying for Hot Trips

• Reflective window covers / silver blockout for the sun-facing windows
• 12V fans (one per sleeping space)
• Awning walls (shade the awning area)
• Spare water — much more than you think you'll need
• Cold packs / esky for fridge backup if you lose power
• Electrolyte sachets for hot active days

When to Bail

Some conditions you don't camp through:

• Catastrophic fire danger forecast
• Forecast 45°C+ with no shade available
• Heatwave with no power (powered sites at least give you reliable aircon)

Better to bail to a powered site, a town with aircon, or back home than to tough it out and have someone get hurt.

Related: Truma Aventa Aircon Guide · Dometic FreshJet Aircon Guide · Cold Weather Camping