Clothing/Shoes/Weather Gear: This is a walking town so take comfortable shoes. It will probably rain while you are out so take a water repellant wrap or umbrella with you. Dress warm when you go to see the penguins because it is cold and windy out on the island.
We visited Punta Arenas during late spring (early December) and still it can be ‘winter’. Specially when visiting the penguin colonie (sometimes with a boat trip) it can be (very) cold. Besides the weather can change very quickly; during our visit we had rather good weather in the morning in Punta Arenas and in the afternoon at Seno Otway it was cloudy, very windy and very cold.
What to pack for Punta Arenas (and Patagonia)
Clothes: best to wear in layers
Wind- and waterproof jacket
Good shoes (specially if you intend to do the trekking on the glacier)
Hat/cap and gloves
Toiletries and Medical Supplies: UV filter sun glasses and Sunscreen lotion, 30+ (the sun is very intensive, even if there are clouds)
Photo Equipment: Enough space on your memory card.