does anyone know what the hi/low temperatures are for this time of year?

http://www.nps.gov/grsm/planyourvisit/weather.htm Check this link it will give you some idea of what to expect.

But it can vary wildly so prepare for anything. We had 70s in mid March and wore t-shirts and shorts in '07. And I carried my down jacket and yak trax in there! (but needed it in April. Crazy stuff) :)

Variable time of year for the smokies. Prepare for both warm weather and/or cold.

It will most likely be very cold. But march can also go either way. Check the weather before you go and maybe you'll be luckly and have a warm week. The Smokies get the most snow in March according to the park website, so yeah it will probably be cold.

http://www.weather.com/weather/wxclimatology/daily/USTN0196?climoMonth=3&x=12&y=10 This link will give daily averages and record lows and highs for Gatlinburg, remember that the mountain tops will be several degrees colder.