A plant's performance is governed by many climate related factors including the length of the growing season, the amount of rainfall, winter lows, summer highs, wind or humidity.
Various initiatives have taken place to determine how well plants would withstand the cold winter temperatures (Plant Hardiness Zones) or when plants would start suffering from the heat (Plant Heat Zones).
A more sophiticated approach has been followed by Sunset which defines Climate Zone Maps based not only on hardiness or heat tolerance but also on precipitations, wind, humidity and various other climate related factors.
The USDA Hardiness Zone Map divides North America into 13 zones of 10°F each, ranging from -60°F (-51°C) to 70°F (21°C). If you are planning to buy a shrub, perennial or tree, you need to make sure that this new plant will tolerate year-round conditions in your area.