Waterton has highly variable mountain weather, which can change quickly. Summers are brief and cool and winters are mild and snowy, with frequent warm spells caused by chinooks.
two opposing systems strongly influence Waterton's climate - Arctic Continental (cold, dry) and the more dominant Pacific Maritime (warm and moist)
Wind is the most important climate factor in the park. After the Crowsnest Pass, Waterton is the second windiest, warmest places in Alberta. Average daily winds of 32 km/hr (20 mph), though max. 120 km/hr (75 mph) are not uncommon. Highest winds blow in January and November, with gusts of over 150 km/hr (90 mph) recorded in the main valley. Prevailing winds are from the southwest.
Waterton has one of the highest chinook frequencies in Alberta (about 28 winter days with temperatures of 2.5*C and above); which cause it to be one of the warmest areas in Alberta in winter. Temperatures can rise dramatically in short periods of time.
Waterton receives Alberta's highest average annual precipitation levels - 1,072 mm. Cameron Lake receives an average annual precipitation of 152 cm (60 in); the townsite 107 cm (42 in); the park gate 76 cm (30 in).
Average winter snowfall in townsite is 575 cm (225 in), higher in mountains.
January and February are coldest; temperatures can drop to -40*C.
June and April are the cloudiest and wettest months.
Waterton's weather is variable and can change quickly. Summers are brief and cool with some hot spells (high 35*C/94*F). Winters are long and relatively mild, with frequent warm spells (high 10*C/50*F), usually caused by chinooks. On average, Waterton is one of the warmest places in Alberta in winter although winter temperatures can drop as low as -40*C.
The park's climate is influenced by two opposing systems - the Arctic Continental (cold, dry) and the prevailing Pacific Maritime (warm, moist). The more influential Pacific system gives Waterton high precipitation and frequent chinook winds.
WHAT IS A CHINOOK?
It's a strong wind that becomes warm and very dry while rapidly descending the lee side of mountain slopes. The wind turbulence is similar to the action river water makes when it hits a rock. As the air flows down, waves are created. The high crest of the wave creates a distinctive cloud band parallel to the mountains called a chinook arch.
WHERE ARE THEY FOUND?
They're found where prevailing winds cross mountain ranges situated parallel to them. They're particularly strong in southern Alberta and northern Montana. Chinooks also occur in other parts of the world including Germany, Switzerland, New Zealand and Argentina.
HOW FREQUENT ARE THEY?
Chinooks can happen year-round, although the warming condition is more apparent in colder weather. A chinook can last less than an hour or for several days. Not all east slope winds are Chinooks.
WHY DO THEY HAPPEN?
Winds carrying warm, moist air from the Pacific glide up and over the western slopes of mountains - expanding, cooling and losing moisture. Once over the Coast and Rocky Mountains, the now-dry air plummets to the foothills, warming by compression. For every 100-metre drop in elevation, temperature raises 1*C. Chinook winds blow from the south or southwest and can reach speeds over 150 km/h.
Source: Environment Canada, 1995.
Wind, with an average daily velocity of 30 km/hr, is the most important climate factor in the park.. While gusts of over 100 km/hr (60 mph) are common in the Fall and Winter, gusts of over 150 km/hr. (90 mph) have been recorded in the main valley. Prevailing winds are from the southwest.
The park also receives Alberta's highest average precipitation levels - 1,072 mm annually. Comparatively, the Columbia Icefields receive 930 mm. This difference is likely the result of fewer and lower mountain ranges between Waterton and the Pacific - the Coast Ranges and the Rockies. To reach the Icefields in Banff and Jasper, a Pacific air mass must cross the Coast Ranges, the Monashees, the Selkirks, the Purcells and the Rockies. There are also big differences in moisture levels from west to east across the park. Cameron Lake, at the continental divide, receives an average of 152 cm (60 in) annually while the townsite receives 107 cm (42 in) and the park gate receives only 76 cm (30 in)! Moist air ascending peaks at the divide has its moisture wrung out as it rises and cools. There tends to be a "spill-over" effect in the Cameron Lake area, making the area quite moist. As descending air warms and sweeps out onto the prairie, it can hold more moisture so will tend to have a drying effect.
As with most places along the continental divide most of Waterton's precipitation falls as snow (575 cm./225 in. at townsite). When cold Arctic air moves under moist Pacific air, heavy snows fall. Waterton's winds play a major role in redistributing this snow. Windward slopes in the park are scoured bare while leeward slopes accumulate large amounts. The importance of this redistribution is twofold - windswept slopes form critical forging areas and travel corridors for wildlife and slow melting snow packs sustain streams and rivers during the summer months.
Spring in Waterton arrives in a swirl of meltwater. In most years, runoff is contained in streams, rivers and lakes then absorbed by soil and plants. Occasionally, a combination of a large heavy June rains, warm temperatures and large melting snowpack has resulted in flooding. Recently, large floods have occurred in 1953, 1964, 1975 and 1995. Flooding is an important natural process which contributes to building and shaping the landscape. For example, the alluvial fans of Blakiston and Cameron creeks grow and are replenished with nutrients. The Blakistan fan provides important habitat for ungulates and the Cameron fan has provided a prime location for the townsite. Although floods are beneficial for natural habitats, they can be destructive to human habitats. Parks Canada has tried to reduce the threat of floods by straightening and reinforcing the banks of Cameron Creek where it flows through town.
Waterton's unique climate - with its high precipitation, frequent strong winds, chinooks and mild temperatures - influences the variety and distribution of the park's plants and animals. Its slightly maritime climate favours the growth of plants like beargrass, false huckleberry and ninebark. In contrast, wind-dried east slopes favour grasses and limber pine. This climate is a significant factor behind the diversity found within this small park.
Brady, K.S., R.A. Watt and K.E. Seel. 1984. Waterton Lakes National Park - Resource Description and Analysis - Volume 1. Western Region, Parks Canada, Alberta.
Janz, B. and D. Storr. 1977. The Climate of the Contiguous Mountain Parks. Environment Canada, Atmospheric Environment, Toronto, Canada.
Hare, F.K. and M.K.Thomas. 1979. Climate Canada - 2nd Ed. John Wiley and Sons Canada Limited, Toronto.
If you would like more information please e-mail Parks Canada (Waterton Park) at email@example.com
Parks Canada - Waterton Lakes National Park main number 403-859-2224