Predicting the weather in Vancouver can be a meteorologist's nightmare. The variations between the coast and the mountainous terrains, the influence of sea breezes, and the "Pineapple Express" (a phenomenon that brings warm rain in the winter and which produced the distinct lack of snow during this year's Winter Olympics) all add to the challenge.
Vancouver lies on the western seaboard of Canada, with the vast expanse of the Pacific Ocean to the west and the Rockies to the east. Since the prevailing wind direction is from the west, the influence of the Pacific gives Vancouver a maritime climate, which moderates its temperatures and increases rainfall.
The city is also tempered by the warm Japan Current, similar to the Gulf Stream in the Atlantic Ocean which provides a warmer climate to the UK.
Vancouver is in fact the second-warmest city in Canada, despite the relatively cool summers. Plants that would normally perish at such northern latitudes can survive due to the warming effects of the ocean currents.
Summer months are typically dry with plenty of sunshine, as high pressure systems dominate. July and August are the sunniest and driest months, when drought conditions often begin to take hold. During the height of the summer, twilight can extend the length of each day until well after sunset.
In contrast, the rest of the year is particularly wet. Vancouver is often referred to as the "rainy city", but how soaked you get depends what time of year you visit. It is not unusual to experience many consecutive days of damp conditions between November and March.
Winters are typically mild, although Arctic blasts can occasionally interrupt the prevailing westerly flow. Heavy snowfall is a common winter occurrence in the more mountainous areas of Greater Vancouver – hence its popularity as a skiing destination. However, snowfall is lighter and less frequent in the city itself, where the snow tends to be quite wet and short-lived. There have been exceptions to this, with some snow events leading to over a metre of the white stuff in the city.
Dr Liz Bentley is founder of The Weather Club, formed by the Royal Meteorological Society to promote an appreciation and understanding of the weather. Visit theweatherclub.org.uk for more information