Hi Margaret,
When it comes to weather, Vietnam’s climate is so diverse. Think frosts and occasional snow in the mountains of the north, and temperatures soaring to 40°C in the south during the dry season.
Vietnam’s weather is dictated by two monsoons. The winter monsoon comes from the northeast between October and March, bringing damp and chilly winters to all areas north of Nha Trang and dry and warm temperatures to the south. From April or May to October, the summer monsoon brings hot, humid weather to the whole country except for those areas sheltered by mountains. From July to November, violent and unpredictable typhoons hit central and northern Vietnam.
All our Vietnam tours require you to be fairly fit as you walk a fair distance due to the amount of sightseeing included. We suggest you take a comfortable pair of walking shoes/boots, sun cream, sunglasses and a hat. We would also suggest you take a small rucksack to carry drinks etc.
The Vietnamese dress very conservatively. Women and men wear long pants and short or long sleeve tops for the most part. Quite a few Vietnamese wear Capri’s (cropped pants) pants and sleeveless tops. Due to the heat women seem to wear Carpi's or pedal pushers and short sleeve or sleeveless tops.
There will be plenty more information online and also fellow travellers who are members of the community I'm sure will offer some useful insight,
I hope this helps,
Kindest,
Ben