Post-Wet Season Car Detail Checklist for Cairns (March–April Must-Do)

It's March. The worst of the wet season is behind us. Cairns just copped somewhere between 1,500 and 2,000mm of rain over the past four months — plus cyclone threats, 90%+ humidity, and daily afternoon storms that turned every car park into a temporary lake.

Your car survived it. But it didn't come out unscathed. Here's what to check and what to do about it.

What Wet Season Just Did to Your Car

Even if you kept your car garaged, Cairns' wet season affects vehicles in ways you don't always see immediately. The combination of extreme humidity (regularly above 85%), heavy rainfall, warm temperatures, and salt-laden coastal air creates a cocktail that attacks every part of your vehicle — inside and out.

We see the same patterns every March. Cars that looked fine in November now have mould under the seats, water spots etched into the paint, and a musty smell that won't go away with an air freshener. The good news: almost all of it is fixable if you catch it now. The bad news: leave it until June and some of the damage becomes permanent.

Interior Check: Mould, Smell, and Damp

This is where wet season hits hardest. Your car's interior is essentially a sealed box that's been sitting in 85%+ humidity for four months. That's a mould factory.

Where to Look

• Under the seats. Pull the driver and passenger seats forward and check underneath. Mould loves dark, damp spaces with no airflow. Any food crumbs or spilled drinks from months ago are now mould food.
• Seat belt webbing. Pull the belt all the way out and inspect it. Seat belts absorb moisture from hands and humidity, and mould can grow in the fibres where they retract into the pillar.
• Boot/trunk carpet. Lift the boot carpet and check the spare tyre well. Water can enter through worn tail light seals or boot seals and pool underneath without you noticing. We've found standing water in boot wells more times than we can count during March inspections.
• Door jamb seals. Run your finger along the rubber door seals. Green or black mould often forms in the folds of the rubber.
• Headlining. Look up. Water stains on the headlining mean a leak — possibly from a sunroof drain, antenna seal, or roof rack bolt seal.

The Smell Test

Close all windows, leave the car sealed for an hour on a warm day, then open the door and smell. If there's a musty, earthy, or damp smell — you have mould somewhere. It might not be visible yet, but the spores are there.

Don't mask it with air freshener. That's covering the symptom while the problem grows. You need the mould source found and treated properly.

Exterior Check: Spots, Oxidation, and Contamination

Four months of tropical rain does specific things to your paint:

Water Spots

Cairns' rain isn't pure water — it carries minerals, dust, and airborne contaminants. Every time it rained and dried on your car (which happened roughly 100+ times over wet season), a fresh layer of mineral deposits was left behind. By March, some cars have so many layered water spots that the paint looks permanently hazy. See our full water spot removal guide for the detail on this.

Oxidation

The combination of UV (yes, even on overcast wet season days, UV levels in Cairns are extreme) and moisture accelerates paint oxidation. Horizontal surfaces — the bonnet, roof, and boot lid — cop the worst of it. If your paint looks dull or chalky compared to how it looked in October, oxidation has set in.

Contamination

Tree sap, bird droppings, bat droppings (a very Cairns problem — flying fox colonies near the Esplanade and other roost sites), and insect residue all bond more aggressively to paint in warm, humid conditions. If these have been sitting on your paint through wet season without being washed off promptly, they may have etched into the clear coat.

Rubber and Trim

Rubber trim, window seals, and plastic components can develop a white, chalky appearance after prolonged UV and moisture exposure. This is surface oxidation of the rubber/plastic — it's cosmetic but makes your car look older than it is.

Underbody: The Damage You Can't See

This one gets missed because you can't see it without getting under the car. But it matters — a lot.

During wet season, Cairns roads flood regularly. Even shallow standing water carries silt, debris, and road chemicals that spray up into your underbody, wheel wells, and suspension components. If you've driven through any flooded sections (and in Cairns, that's almost unavoidable), debris may be trapped in cavities underneath the car.

Salt air compounds this problem. Salt deposits on metal underbody components accelerate rust formation, especially on older vehicles or cars without factory underbody protection.

What to do: An underbody wash and inspection. We use a pressure washer to flush out wheel wells, suspension mounts, and chassis rails, then inspect for any signs of surface rust forming. Catching rust early means treating it with a rust inhibitor for $50. Missing it means panel repairs for $500+ down the track.

AC System: Mould in Your Vents

Here's one that affects your health, not just your car. Your car's air conditioning evaporator sits inside the dash, and during wet season, moisture constantly condenses on it. This creates a permanently damp environment inside the AC system — perfect for mould growth.

If your AC smells musty when you first turn it on, that's mould. You're breathing in mould spores every time you drive. In Cairns' climate, this is extremely common — we'd estimate 7 out of 10 cars we inspect in March have some level of AC mould.

The fix: An anti-bacterial AC treatment. We run a hospital-grade sanitiser through the AC system that kills mould spores on the evaporator and throughout the ducting. It takes about 30 minutes and the difference is immediate — your AC blows clean, fresh air instead of musty air.

Cost: $80–$120 as a standalone service, or included in our full post-wet season reset package.

The Full Post-Wet Season Reset

Here's what we recommend as a complete post-wet season reset. This is the checklist we work through for every car we detail in March and April:

Interior

• Full mould inspection — seats, carpets, boot, door seals, headlining
• Mould treatment with anti-microbial solution where needed
• Hot water extraction on carpets and fabric seats
• Leather clean and condition (humidity dries out leather — counterintuitive but true)
• Ozone treatment for odour neutralisation
• AC anti-bacterial treatment
• Dashboard, console, and trim deep clean
• Window track and seal cleaning

Exterior

• Decontamination wash (iron fallout remover + clay bar)
• Water spot assessment and removal
• Paint correction for oxidation and etching if needed
• Rubber and trim restoration
• Wheel and tyre deep clean
• Underbody pressure wash and inspection
• Protective sealant or ceramic boost application

A full post-wet season reset for a sedan typically runs $350–$500. SUVs and 4WDs run $450–$650. It's a bigger job than a regular detail because we're undoing four months of tropical punishment — but it's the single best thing you can do for your car's long-term condition.

Why This Is the Most Important Detail of the Year

If you only detail your car once a year, this is when to do it. Here's why:

• Mould doesn't wait. Left alone, mould spreads through carpet backing, seat foam, and headlining material. What's a $100 treatment in March becomes a $400+ full interior restoration by July.
• Water spot etching is progressive. Mineral deposits left on paint continue to etch deeper with UV exposure. Spots that are correctable with a single-stage polish in March may need multi-stage correction (2x the cost) by June.
• Rust starts small. Surface rust on underbody components is cheap to treat now. Left through another wet season, it becomes structural.
• Your car's resale value. Wet season damage that's left untreated permanently ages your vehicle. Cars in Cairns depreciate faster than southern cities partly because of this — owners who maintain through wet season protect their investment.

Bonus: Dry Season Prep

While we're resetting from wet season, it's smart to prepare for what's coming next. Cairns' dry season (May–November) brings its own challenges: relentless UV, low humidity that cracks rubber and leather, and dust.

• Ceramic coating or sealant application. Dry season is the ideal time to apply ceramic coating — you've got a reliable 7-day cure window with no rain risk. Post-wet season correction + ceramic coating is the best combo we offer.
• Leather conditioning. The switch from extreme humidity to dry air causes leather to crack if not properly conditioned. A good leather treatment after wet season sets you up for the dry months.
• UV protection. Your paint just survived wet season — now it faces 6 months of some of Australia's highest UV levels. Sealant, ceramic coating, or at minimum a quality wax creates a barrier against UV oxidation.

March and April are our busiest months for exactly this reason. Everyone's car needs attention at the same time. If you want to get ahead of the queue, book early. We'll come to your place, run through the full checklist, and get your car reset properly before the dry season hits.