Should I bring a heavy rain jacket?

No. It is too hot and humid. Bring a thin, breathable shell that keeps rain off but allows sweat to evaporate.

Do I need to worry about mold?

Yes. Keep a few silica gel packs in your bag, and never store damp clothes in your main compartment. Air out your gear every time you reach your accommodation.

Packing for Monsoon Season in Southeast Asia

Prioritize high-quality waterproof gear and focus on synthetic, fast-drying fabrics that won't hold moisture. Keep all electronics in double-layered dry bags, and choose footwear that provides traction on slick, tiled surfaces.

Waterproof your luggage. Don't rely on your backpack's 'water-resistant' cover alone. Line the interior of your pack with a heavy-duty trash compactor bag or a dedicated internal dry bag liner to keep your clothing bone-dry during heavy downpours.
Select fast-dry fabrics. Avoid cotton entirely; it stays wet for days and breeds bacteria. Pack lightweight merino wool or synthetic tech-fabrics (polyester/nylon blends) that can dry overnight even in 90% humidity.
Protect your electronics. Use individual 5L or 10L roll-top dry bags for your camera, phone, and power banks. If you carry a laptop, use a waterproof sleeve inside your pack, as humidity will damage sensitive circuits over time.
Choose the right footwear. Bring one pair of closed-toe waterproof sandals (like Tevas or Keens) for walking through street flooding, and one pair of lightweight trail runners with deep lugs for traction on wet, mossy stone paths.

Should I bring a heavy rain jacket?: No. It is too hot and humid. Bring a thin, breathable shell that keeps rain off but allows sweat to evaporate.
Do I need to worry about mold?: Yes. Keep a few silica gel packs in your bag, and never store damp clothes in your main compartment. Air out your gear every time you reach your accommodation.