From snow-topped mountains and sun drenched beaches, Vancouver has something to offer in every season.
It is not as cold here as you might think. In fact, Vancouver has some of the mildest weather in Canada with temperatures ranging on average from 20 Celsius (70 Fahrenheit) in summer to 0 - 5 Celsius (about 45 Fahrenheit) in winter.
Winter usually brings rain rather than snow. Make sure you are prepared for wet weather and pack warm waterproof clothing.
Wikipedia has additional information and a climate chart for Vancouver.
UBC has its own weather station at the Point Grey campus so that you can check the current conditions.