Do I need to wear a full suit and tie?

In Singapore, yes. In Vietnam, Thailand, or Indonesia, a button-down shirt with dress trousers is usually sufficient for internal meetings, but keep a tie in your bag just in case you are unexpectedly introduced to senior leadership.

Are there cultural colors I should avoid?

Keep it neutral. Stick to navy, white, light blue, and grey. Avoid bright, neon, or overly loud patterns which can be perceived as unprofessional in traditional corporate settings.

Dressing for business meetings in Southeast Asia

Dress one level more formal than your Western office standard, prioritizing natural fabrics like linen blends or high-quality cotton to manage the high humidity. Always keep a lightweight blazer on hand, as office air conditioning is typically set to freezing levels.

Select the right fabrics. Avoid 100% polyester. Opt for linen-cotton blends, merino wool, or performance fabrics that wick sweat. Synthetic materials will trap heat and show perspiration instantly.
Adopt the 'Layering Protocol'. Wear a breathable base layer (short-sleeved shirt or blouse) and keep a structured blazer or light suit jacket on your travel hanger. Put the jacket on only when entering the building or the meeting room.
Standardize your footwear. Stick to closed-toe leather shoes for men and closed-toe flats or loafers for women. You will frequently be removing shoes before entering certain offices or meeting areas; ensure yours are easy to slip on and off without a struggle.
Pack a crease-release spray. High humidity ruins crispness. Pack a travel-sized bottle of wrinkle-release spray (or plain water in a spray bottle) to spritz your garments after unpacking to drop the travel creases without an iron.

Do I need to wear a full suit and tie?: In Singapore, yes. In Vietnam, Thailand, or Indonesia, a button-down shirt with dress trousers is usually sufficient for internal meetings, but keep a tie in your bag just in case you are unexpectedly introduced to senior leadership.
Are there cultural colors I should avoid?: Keep it neutral. Stick to navy, white, light blue, and grey. Avoid bright, neon, or overly loud patterns which can be perceived as unprofessional in traditional corporate settings.