Your weather doesn't seem that different from Vancouver, BC.
Main thing is to keep your eyes open, it can be amazing what you will see when you are looking.
You might also just be far enough north to find queens and/or colonies in a slightly different manner than many of our southern members. They deal with heat and drought, and their ants dig fast and dig deep.
More northern ants don't usually dig that deep. I have a friend in Vancouver who always finds founding queens under rocks when working in his garden. Just before noon, go turn over some rocks and see what you see. If you see a queen (without wings) collect her first, then grab as many workers and brood as you can. If you don't see her, try another rock. Just before noon, most of the colony will be just beneath the rock warming up. I have stumbled upon countless founding queens, and young colonies like this just when doing yard work.
Also keep an eye on the Ant Mating Flight chart, many members post when they see flights. If they are close to you, then go outside and check.
Do you have a dog? Spoil him/her by going for walks in the morning, afternoon and evening, while looking for queens.
In my location, I have only once ever seen a founding chamber. I have seen thousands of queens on flight, or scurrying along the pavement, or underneath objects yet I have only seen that one founding chamber... I also find lots of Camponotus when splitting fire wood.
Best of Luck!