I know that all guides advice to go between November and April, but if we would be going with the kids, 3 weeks would only be possible during summer holidays...
A lunacy?
Do we have to forget it right away?
What would be the hard part?
In short, some advice please...

Take a look at www.weatherbase.com and check each location in VN that you want to visit.

Thanks Kathie.
This is info I have, but how is it in practice? Extremely humid? Regular rain fall every day at the same hour? Pouring down for hours?
Anyone lived there?
Do you stay inside the house at certain moments of the day? ???

I was in Vietnam in July of 2002: it was humid, but pretty much like the East Coast of the US at that same time. Generally it wasn't a steady all-day rain, just enough to get you cooled off for about five minutes (and, in one case, to share an umbrella with a lovely elderly lady in Hanoi who managed to communicate about her children.)

My trip report is here:
http://www.fodors.com/forums/threads...p;tid=34659821 This might give you a slight taste of what it was like. (I'm planning for India this July; it'll be worse, from the sounds of things, but that's what happens when you have to travel in the summer. Also why I love Iceland.)

Where do you live? Maybe we can give you a comparison.

Bisbee,
I'm in Switzerland.

Amy,
I just read your extensive trip report. Well done. I can cross check everything with my tourist guides now..
Thanks a lot.

It will be quite hot, very humid and might rain. It won't rain everyday, but when it does, it comes down in multiple centimeters. Usually lasts at most an hour, but can be longer/shorter. Benefit is that it helps cool things down a bit. In the South, it usually starts up sometime after 2pm.

You can't control the weather, so why let it control you?

I will be in Vietnam in July as well, as a professor can't get three weeks off during the more "desirable" months. My view is~ just dress appropriately~! Guidebooks say not to bring raingear, as you can by umbrellas, ponchos, etc., for very cheap there.