In most areas of BC and Alberta the campgrounds don’t even open until May long weekend ( Victoria Day weekend which is the third Monday in May. The reason for that is the fear of water freezing at night in the campground infrastructure, and lack of tourists in cool / cold weather. During the weekend a earlier opening campground might be nearly full, but come the weekdays they clear out and only leave a few of us retired people to keep the outhouse toilet seats warm. Pretty hard to justify keeping people on the payroll when they are only providing service to a few campers during the week days.
This is not to say there aren’t campgrounds , Provincial, national, community or private open early, however if your planing on staying in Campgrounds the farther north you go the colder it will be.
The spring of 2017, 18, 19, 20 and 21 were very warm up here, my wife keeps a travel camping log book and those years we started camping in the bush early.
In 2020 one FSRS ( Forrest Service Rec Site, which are off road campsites with no amenities) we got into at the beginning of May which is unheard of, usually we are in some snow and have in the past got some snow over night.
Last spring we started camping at the beginning of May and we froze our butts, wind, cold rain and yes…snow, and kept freezing our butts until the end of June. Our last day camping before the July 1st long weekend ( Canada day) when we woke up there was fresh snow on the mountains above us.
You can travel anywhere you want at any time of the year if your prepared. Myself I wouldn’t heading north until at least the 2nd to 3rd week of May. Heck last spring I was snowmobiling the 1st week of April and we only live 3 hrs north of Spokane Washington in British Columbia.
Good luck on your adventure
Soup.
This was May 21, 2022, about 2.5 hrs north northwest of the Washington BC boarder above Spokane.