There could be a lot of unhappy campers this May long weekend as a snowfall warning covering parts of southwestern Alberta was issued Saturday.

Airdrie, Banff, Canmore, Cochrane, Nordegg, Olds, Rocky Mountain House and Sundre are covered by the warning.

Environment Canada says each of those communities can expect between 10 and 20 centimetres of snow between Saturday and Sunday afternoon.

"Heavy wet snow may cause tree branches to break," Environment Canada said in the warning.

"Rapidly accumulating snow could make travel difficult over some locations. Visibility may be suddenly reduced at times in heavy snow."