I've used my webers at temps lower than -30c, but not often. When it's that cold, there is usually no wind, so that is thankfully not a problem. Everything is frozen stiff, including the suspension on the cars, tires lose their air pressure, and so on. Frozen engines with flat batteries is a common problem, even here in Norway, where these conditions are quite normal each winter in parts of the country. My WSM and grill works as they usually do, using a tad more of fuel. That's it.
You will have to enjoy your beer from the inside. Take it out, and it is frozen solid in ten minutes.