Are there any places that require winter tires by law that don’t have cold winters? I don’t know of anywhere in the US that even requires winter tires, although I think some states require you to have winter tires OR chains.
It would only make sense to require them every winter if the large majority of winters were quite cold. As such, nowhere in the US requires winter tires, but someone else noted that Quebec does. This makes sense, since even a mild Quebec winter will spend most of the time getting below freezing.
I would be very surprised if there were a place that required winter tires by law where the winter does not always get and stay at or below freezing for significant periods of time almost every winter.
(But the winters are cold).