As Alberta extends for approximately from north to south, it is natural that the climate should vary considerably between parallels of
49° and
60° north and also between approximately
110° and
120° west. It is also further influenced by the different altitudes found in the province. In general, Alberta's climate is dry, due to the
rain shadow effect of the
Rocky Mountains and
Pacific Coast Ranges to the west, and
continental, due to its distance from any large body of water. The contrast between warming, dry winds descending from the Rockies and proximate cold air in
Yukon, however, gives Alberta (and the adjacent
Mackenzie Basin) during the winter the highest variability in monthly temperatures anywhere in the world. Exceptionally warm winter months in the province can be as warm as
oceanic climates at similar latitudes – for instance
Edmonton averaged in February 1977 – whereas the coldest winter months like January 1950 when Edmonton averaged are comparably cold to such Siberian localities as
Aldan,
Sakha.
Southern Alberta Most of
Southern Alberta east of the Rockies and outside of the
Cypress Hills, especially
Palliser's Triangle, is a dry
steppe, with most locations having an annual average
precipitation of 280-430mm. Under the
Köppen climate classification, most places in Southern Alberta are either
semi-arid (Köppen climate classification
BSk
), or
humid continental (Köppen climate classification
Dfb) (the "humid" designation denotes that these climates do not meet the criteria to be semi-arid, not that they necessarily have high humidity levels). Most places in Southern Alberta that fall under the "humid continental" classification are close to the borderline between semi-arid and humid continental. The other climates in this area are
semi-monsoonal humid continental (Koppen:
Dwb) located around
Calgary, or subarctic (Koppen:
Dfc) located in high elevation areas and the Cypress Hills. This region has the hottest summer temperatures in Alberta and quite cold winters, though
chinook winds ameliorate the cold winter temperatures temporarily when they pass over. The natural vegetation of this region is mainly dry
mixed grass prairie, grading to mixed grass prairie, and then
fescue prairie as precipitation increases with higher altitude and / or latitude. This area is prone to drought and farming here is not successful without significant
irrigation.
Central Alberta Central Alberta has a dry
continental climate, with most places falling under the humid continental classification (Köppen climate classification
Dfb), though some areas in the southeast of this region, close to the border with
Saskatchewan around
Oyen, are semi-arid (Köppen
BSk). Precipitation levels here are generally higher than in Southern Alberta, though the driest areas of Alberta, around
Empress, are in Central Alberta. This region generally has cooler temperatures than Southern Alberta in both summer and winter, due to the decreased amount of
solar radiation received, and the lower frequency of chinooks blowing through the region. After
Southern Ontario, Central Alberta is the region in Canada most likely to experience
tornadoes. Most of Central Alberta is covered by
aspen parkland, but the driest areas have mixedgrass and even dry mixed grass prairie, while the wetter and/or cooler areas are covered in
mixed boreal forest. The wetter parts of this region, around Edmonton, have some of the most fertile land in the
Canadian Prairies.
Northern Alberta Northern Alberta is the coldest region of Alberta, with most places having a
subarctic climate (Köppen climate classification
Dfc) though some areas in the south of this region, as well as much of the
Peace River Country, have a humid continental climate (Köppen climate classification
Dfb). Winters in Northern Alberta are long, and cold, while summers are short and warm. Precipitation levels are generally lower than Central Alberta and similar to Southern Alberta, but lower
evapotranspiration results in there being greater effective precipitation than Southern Alberta. Natural vegetation in Northern Alberta consists primarily of mixed and
coniferous taiga, with aspen parkland in the Peace River Country. With the exception of the Peace River Country, this region is generally quite poor for agriculture.
Rocky Mountains and Cypress Hills Lower elevations of the
Rocky Mountains and all but the highest elevations of the
Cypress Hills have a humid continental climate (Köppen climate classification
Dfb). These areas have snowy but mild winters due to the warming effect of chinook winds, and cool summers due to their high elevation. As altitude increases and the
subalpine zone is reached, this grades into a subarctic climate (Köppen climate classification
Dfc), with harsher winters and even cooler summers. Above the
tree line, an
alpine climate (Köppen climate classification
ETH) prevails. Conditions this high are even colder and very windy. Precipitation is higher in these elevated regions than elsewhere in Alberta, and this supports forests of
lodgepole pine and
trembling aspen mixed with fescue grasslands in the
montane areas,
Engelmann spruce and
subalpine fir forests in the subalpine zone, and
heather,
sedges and
mountain avens in the
alpine zone above the tree lines. == Ecology ==