You may hit snow in Banff / Jasper / Lake Louise in May, or any other month of the year. However it will usually be gone by the next day. Try to keep an eye on the weather reports from local radio stations if you don’t have internet. If the snowmocmcomming just sit where your at and enjoy the snow, like I said it will usually be gone by the next day, or at least the roads will be clear of snow by the next day. My oldest daughter lived between Calgary and Banff and we drove back and forth for the West Kootenays many times over the years and in different seasons as well. I think it was three years ago and just before the beginning of August that is snowed at Banff. The next day the roads were clear and everyone got to the the Rockies covered in snow for a few hours the next day before the sun melted it.
As for BC ..
Same thing here, except it hardly ever happens on Jun through September where I live which is in the West Kootenays of B.C. June is when like other have said we start to get the big spring melt and some of the rivers and creeks run wild. Always stay away from the banks of rivers and creeks this time of year, usually someone will go in to chase a dog that fell in a creek every spring. The dog is found wet and tired, the owner usually not so lucky.
All hwys will be open in BC, we don’t close them for the winter unless they lead someplace where there is no winter activities, ( homes / resorts etc...) there are seasonal roads that co use still be closed and there will usually be gates and signs stopping you if they are closed. The highest Hwy pass in a Canada that is open years round is not in the Canadain Rockies but in the west Kootenays of B.C. and it only closes in the winter for avalanche control.
We are getting a dump,of snow this year, but if we have a spring like we did last two years it will melt fast. Heck two years ago we had green grass and leafs of the trees where we used to seasonal camp at a mountain lake.
You should have no problems at all for the ti e of year you plan on traveling. Bring an extra blanket for the bed, and a extra warm jacket. If it snows park the rig and have some fun playing in the snow, it usually will be gone the next day. Don’t rush your trip and have fun.
Most campgrounds will be nearly empty the time of year your traveling north, however come the Victoria Day long weekend ( third Monday in May) and the last week of June things will start to get busy unteil after Labour Day weekend.
July 1st is Canada day and August 1st is called different things in different provinces in B.C. it is “ BC Day” campground will be packed on those three weekend and labour days weekend. The farther north you go the less people in the campgrounds.
Lots of small mountain lake campgrounds around where I’ll live hardly get noticed in the summer and are usually only full on long weekends.
Have fun and be safe
Soup.
