As the region is a polar desert (defined by its low rainfall), cloudless days and minimal precipitation are common. However, if rains are to happen, it is most common between July and early September. These are unlikely to perpetuate the whole day and in the comfort of your polar vehicle you will be warm and dry.
Hundreds of thousands of caribou are often seen during this time, feeding on the summer grasses of the tundra before preparing for their migration in September. You may also be lucky enough to spot the rare musk oxen, with their shaggy coats and inward-facing horns along lake shores and rivers.
August is a popular time to travel to Arctic Canada and therefore prices with be high and availability limited.