When to visit Banff National Park
Summer (June to September)
The best time to visit the mountains for the sake of the scenery and hiking is June through September. That is when the mountain lakes are thawed and the brilliant turquoise colour of their water can be enjoyed. The mountain resort towns of Banff, Lake Louise and Jasper tend to be crowded in July and August. So, if you have the flexibility to avoid the busiest season, it is better to visit the area in June or September.
But if you can only travel in the busier months of July and August, it is still definitely worth visiting the area. When it comes to the Canadian Rockies, "busy" is a relative term. The Rocky Mountain national parks cover a large area over 22 000 km2, and it takes only a little effort to step into the forest and away from the crowds, the local's secret to escaping the hoards is by staying out at one of the rustic wilderness hostels along the Icefields Parkway.
Fall in the Canadian Rockies
September ushers in the yellows and golds of autumn. The aspen trees around Banff are at the height of their colour around the middle of September, and the larches around Lake Louise are at their golden best towards the end of September. Jasper, being at a slightly lower elevation than Lake Louise and Banff, has a slightly later fall. It usually is at the height of its colour around the beginning of October.
October is a transitional month. This shoulder month can provide pleasant weather. On the other hand it also can produce blizzards. The beginning of October is the time at which some trails and side roads in the mountains start shutting down for the winter. Activities and access to scenic landmarks remain fairly good up to and including Canadian Thanksgiving , which is celebrated on the second Monday of October. But, by the middle of October, many winter closures have taken effect. So, depending on the kind of experience that you are looking for, October can be a somewhat risky month. On the other hand, it is a month in which the mountain resort towns are quieter and service is more attentive and the local Ski Areas Sunshine Village, Lake Louise Ski Area and Norquay hold their annual hiring clinics, interviewing staff from around the world for the chance to spend the winter season working on the slopes.
November is an extremely quiet month in the mountains. Summer sightseeing and hiking are over, but downhill skiing has not yet begun.
Winter: December to March
Downhill skiers visit the mountains from December through April and even into early May. The prime skiing season is February to April.
May is another transitional month. It is a month in which the traveler may encounter anything, from snow storms to summer weather. The mountain lakes tend to thaw towards the end of May. Yet a few of them, like beautiful Moraine Lake , are not yet looking their turquoise best till after the first week of June.
Something that affects your vacation experience is the number of daylight hours. In the summer there are between 14 and 16 hours of daylight. In the autumn that drops down to about 10 hours of daylight per day. On the winter solstice, there are just under 8 hours of daylight. Then in March daylight increases to around 12 hours. The long summer days have their advantages. The many hours of sunlight make it easier to keep going and see more. On the other hand, the reduced daylight hours of the fall make it easier to be up in time to photograph sunrises. Also, since animals are more active at dawn and dusk, in the fall you have a better chance of being out and about at the same time as the wildlife.