Are you getting snow this morning, JoJo?
I enjoy looking at maps, JoJo. They draw me to places I've never been. And, I haven't been to Lillooet. I've turned east to Kamloops rather than west towards your city there in the mountain valleys. You should know that your "extreme minimums" there in Lillooet are -26C in January even if you are only living at 200 meters elevation.
National Climate Data
Here's a map issued by the Canadian government for hardiness zones:
Natural Resources Canada Click on your part of the world until British Columbia is centered and then increase the map size up to XL.
Sure enuf, your garden in Lillooet could be a zone 6! The valley around appears to be mostly zone 5 and since the nearby terrain is so steep, it really depends on elevation how one might designate their home there.
Where I garden, hundreds of miles to your southeast, the winter climate is similar to the Kootenai River valley. Once again, elevation makes a big, big difference. It's a little drier here than on the Kootenai, however. Not drier than your home, perhaps, but it isn't too far to the Columbia Basin desert from here. It could be that few people reading this ever think about a desert in the "Evergreen State" of Washington. Let me assure you, there are plenty of Washingtonians on the other side of the mountains who never think about the eastern side of the state either

.
I was reading just the other day about how northern Idaho became a part of Idaho rather than Washington. It was a part of Washington territory at one time. Well, it was a decision by the government in Olympia . . . The politicians felt that the Idahoans would be so difficult to govern and their interests so different from the interests of people on the Puget Sound that they were happy to let them go

.
My family came here in 1895 but seemed to have a real problem deciding whether they wanted to live in Washington or Idaho

. And, once here in the West, their family connections developed from southern BC to southern California

.
Since my interests are mostly with garden annuals - winter hardiness mostly means whether I can
stand to live here from November to April

. I recently learned that the
summer climate here is very, very similar to northern Spain

! I can't tell you how interested that makes me in what the Spanish people are growing in their gardens!!
Steve