Environment Canada is warning up to 15 centimetres of snow could fall by Wednesday at higher elevations in the mountains west of Calgary.

A system moving through the northwestern United States is to blame for the wintery weather, which is expected to start as rainfall on Tuesday evening and turn to snow by Wednesday morning.

Between 10 and 15 centimetres could fall throughout the day.

The snowfall warning extends from the Kananaskis and Canmore areas, north to the Nordegg area, while a rainfall warning is in effect for Fort Macleod and Macgrath and a weather warning is in effect for Pincher Creek and Waterton Lakes.

The forecast for the May long weekend in Calgary calls for highs of 16 C to 18 C with cloudy periods and a chance of rain.

The forecast is similar for Kananaskis and Canmore over the long weekend, with highs between 16 C and 18 C expected, and overnight lows of around 4 C.