Since Vancouver is a coastal and mountainous location, micro-climates exist throughout the surrounding areas. There are local weather variations for many parts of the lower mainland as a result of Vancouver's location.
For instance, many people have visited San Francisco at least once. San Francisco has varied weather just like Vancouver. But Vancouver's surrounding cities are actually even more exaggerated than other coastal cities such as San Francisco. The result is moderately low West Coast temps of 2 to 4°C in winter and 3–8°C or more during the summer months. For instance, the temps during summer in North Vancouver might be 28C while temps out in Abottsford would be 34C.
As a rule, North Vancouver and a few other areas close by get the most rain. Unfortunately, the precipitation is recorded out in Richmond at the Vancouver airport where rainfall can vary some 80mm or more within a day. I certainly don't think someone was thinking when they decided to record Vancouver's weather accurately.
Therefore, predicting precipitation is a very complex issue. The general rule of thumb is that for every rise of 100m in elevation, there is an additional 100mm of rainfall. Predicting what a certain area might be like can also be complex. At times, there can be showers at the airport, snow in Queen Elizabeth Park, rain and down town. Areas such as Tsawwassen, which is just south of Vancouver can get much more sunshine, while areas such as where we live in North Vancouver can see much more rain.
Ironcially, most all of the Olympic venues for 2010 will be spread out from Whistler to North Vancouver to areas such as down town Vancouver, central Vancouver and even Richmond. This will definitely be a large area of complex weather differences.
Here is a small chart of the monthly differences in hours of sunshine we supposedly get.