Australia, New Zealand & the South Pacific - South Island New Zealand: Late May or Late August?

I am looking at a trip to New Zealand (mainly south island) from the US this year. Due to the schedule of work back here in the states, the best times for me to go are either the second half of May or the second half of August. I know that is the winter time there, but I wanted to get everyone's opinion on which would be better: May or August. I envision doing the main things such as see Christchurch, Queenstown, Milford Sound and possibly the glaciers on the west coast. I am not a skier, so the amount of snow in the mountains is not a concern. Just more interested in the general weather and which would be less of a nuisance in terms of temperatures and precipitation. As for getting around, I was planning on doing the coach tours to see most of the sites.

Thanks for any pointers!

If you're not into skiing or other winter activities, I'd go for May. It will still be cold and chance of ice and snow (especially inland and mountain areas) but milder and less wintry than August. Compared to inland and northern parts of US we dont get much snow, but as not generally used to it even small amounts can close roads - especially in lower areas where snow is rarer. For the benefit of others reading this, May is too early for most skifields (in most years).

Some useful info for you to consider.

NZ holidays (public and school holidays) (http://www.flyertalk.com/forum/showthread.php?t=320780)

NZ climate overview (http://www.metservice.co.nz/default/index.php?pkey=190512&class=menu) and data (http://www.metservice.co.nz/default/index.php?pkey=190512&ckey=192937)

May has far better weather. Can be quite nice. While in August you probably can't get to the glaciers if on a tight schedule and even Milford sound is iffy. It sounds you aren't planning to go into the high country, but if you go in August it is possible to be snowed in for a week!!!! My guide on the glacier tour had a great story about his survival training course, which wound up being stranded for 2 weeks due to snowfall of over 10 meters (that is 30 feet!!!!!). Remember that the west coast of NZ south island is a rain forest, and rivers rise incredibly fast at times -- and the road detour may be an extra 200 miles.

I wouldnt worry about 10m snowfalls, or possibility of floods. Heavy rain can occur at any time of year and the west coast is set up to cope with downpours that would cause major problems elsewhere.

The west coast of the south island often has better (although colder) weather in winter than in summer. At any time you could be really unlucky and get a big storm, but you can't really plan for that.

I'd echo everyone else's advice and suggest May - autumn is a good time of year for quite settled weather, and it will be much milder than August. Make sure you bring warm clothes if you want to be doing any outdoorsy things. (Even in summer you should always take warm clothes to NZ - the climate is nothing if not unpredictable!)