I have a trip planned for the last two weeks of March and I'm curious about the weather and what kind of clothes I should be shopping for. We start in Rome and then head north to Venice.
See the FAQ for info on how to learn about the weather. It's permanently the very first topic. Happy travels.
the weather is likey to be all over the map. We have encountered a bit of rain, some nice sunny days in the 60s and then some in the 40s. You'll likely have the best bet with layering and possibly a good rain shell.
http://www.wunderground.com/tripplanner/index.asp The above link takes you to a site where you input a location and span of dates (in your case, say, March 15 to 30), and it then gives you the weather for the last 15 years.
I was on a RS tour in Venice a few years ago in March and the weather was definitely cool and occasionally rainy. I wore a waterproof jacket most days with a hood and was happy with that.