Vancouver is also one of the wettest Canadian cities. However, precipitation varies throughout the metropolitan area. Annual precipitation as measured at Vancouver International Airport in Richmond averages , compared with in the downtown area and in North Vancouver. The daily maximum averages in July and August, with highs rarely reaching . The highest temperature ever recorded at the airport was set on July 30, 2009, and the highest temperature ever recorded within the city of Vancouver was occurring first on July 31, 1965, again on August 8, 1981, and also on May 29, 1983. The coldest temperature ever recorded in the city was on January 14, 1950 and again on December 29, 1968. On average, snow falls on nine days per year, with three days receiving or more. Average yearly snowfall is but typically does not remain on the ground for long. Winters in Greater Vancouver are the fourth-mildest of Canadian cities after nearby Victoria, Nanaimo and Duncan, all on Vancouver Island. Vancouver's growing season averages 237 days, from March 18 until November 10. Vancouver's 1981–2010 USDA Plant Hardiness Zone ranges from 8A to 9A depending on elevation and proximity to water. Cityscape Urban planning Vancouver is the most densely populated city in Canada. Urban planning in Vancouver is characterized by high-rise residential and mixed-use development in urban centres, as an alternative to sprawl. As part of the larger Metro Vancouver region, it is influenced by the policy direction of livability as illustrated in Metro Vancouver's Regional Growth Strategy. Vancouver has been ranked one of the most livable cities in the world for more than a decade. , Vancouver has been ranked as having the third-highest quality of living of any city on Earth. In contrast, according to Forbes, Vancouver had the fourth-most expensive real estate market in the world in 2019. Vancouver has also been ranked among Canada's most expensive cities to live in. Sales in February 2016 were 56.3 percent higher than the 10-year average for the month. Forbes also ranked Vancouver as the tenth-cleanest city in the world in 2007. Vancouver's characteristic approach to urban planning originated in the late 1950s, when city planners began to encourage the building of high-rise residential towers in Vancouver's West End, subject to strict requirements for setbacks and open space to protect sight lines and preserve green space. The success of these dense but livable neighbourhoods led to the redevelopment of