It is the mountains! Weather can change in a flash. Travelling in the mountains here and in Alberta, I've witnessed up to six inches of snow on July 1st and at other times throughout the summer months. No doubt the moisture will be welcomed in some areas.
When my wife and I went south this winter, we left on Jan 26th traveling through Oregon, Idaho and Nevada. I loaded 2 sets of chains tow strap, headlamps, shovel and ax. In addition a heavy coat insulated coveralls, gloves and a stocking cap. My wife looked at me quizzically until she remembered the time of the year and the area we were traveling through. We timed our trip to be between storms and as it turned out had dry pavement all of the way, down and back.
It can snow at any time in the mountains here too, the least likely months are June and July but it can still happen. We had mixed rain and snow yesterday for a while and a bit of snow was in the forecast for the first part of this week.
On my first trip to Canada (back in July of 1979), I was travelling through the Banff area with my host. As we travelled up the parkway, I asked (in all innocence), "What is that pollen blowing in the air?" He nearly wrecked the car because he was laughing so hard. "Haven't you ever seen snow?" he asked. Okay, I'll just hush my mouth.