What you should wear in a country not only depends on the weather of that place but also relies on a dozen of matters related to religion, culture, and the extent to which the local might affect your clothes. Vietnam is not a country that has so many rules and regulations related to how to dress but you are supposed to pay attention to some following tips to enjoy your journey to the utmost.
1 - The North and the South Vietnam have different patterns of climate, not to mention the differences in weather among delta, mountainous and coastal areas. To make sure that you bring the right type of clothes, it is advisable to check out the weather of your destination before you go.
2 - If you do not want to bring much clothes and intend to buy them in Vietnam, being under the impression that clothes in Vietnam would be cheap, well, it's time to wake up! Clothes in Vietnam are only cheap when you know how to bargain and where to buy clothes with fixed prices.
3 - Here are some branded shops in Vietnam that you should drop by to get clothes of your size at reasonable prices without bargaining: Blue Exchange, Made in Vietnam (for both summer and winter clothes) and Canifa (for woolen clothes). In these shops, jeans prices range from 150.000 VND ($7.5) to 250.000 VND ($12.5), shirts prices from 150.000 VND to 200.000 VND ($7.5 - 10) and T-shirts prices from 100.000 VND to 200.000.VND ($5 - $10). Winter clothes prices often increase when the degree drops. You could catch these shops in big cities in Vietnam easily but for a trip to rural areas, you had better prepare clothes in advance.
4 - Coming to Vietnam in the summer, you are likely to be exposed to Vietnam mosquitoes; they are not harmless as you might think. It is sure that you never want to spend your long holidays in hospital due to dengue fever. So, prepare some long-sleeve clothes and insect repellent for hot and humid nights in Vietnam.
5 - Vietnamese people, especially the elderly, dress conservatively and in general it is considered impolite when wearing clothes that show off too much skin. So when in Vietnam, do as the Vietnamese do to avoid curious or even unpleasant stares from the local.
6 - There is an unspoken rule that tourists must dress well when visiting pagodas to show respect for the religion. Shorts and tatty beer t-shirts should be set aside for other occasions. Shoes are fine in most pagodas so taking it off is not necessarily obligatory. Following what the local do is the easiest way to prevent you from any awkward moments.