All extratropical storms are a mixture of warm and cold air.
In parts of the storm, especially the areas ahead of a warm front, warm air is flowing over cold air near the ground. The result is a layer of air that's above 32 degrees Fahrenheit between a layer of colder air near the ground and a layer of colder air higher up. In places where the warmer air extends to the ground, the precipitation will fall as rain. If the layer of cold air near the ground is relatively thin and if things on the ground are below 32 degrees, the falling rain cools below 32 degrees but doesn't turn into ice until it hits something - this is freezing rain. In places where there is no layer of warm air, the snow falls all of the way to the ground as snow.