Rain can freeze on roads even when the temperature is above freezing on the surface.
Rain can turn to ice and sleet as it leaves the sky at 32 F or below and then can cause the road to become slick and even leave a thin layer of ice on the road called black ice.
If it's raining out and the surface of the road is below freezing or at least 32 F or below that then the rain can turn to ice and freeze on the road.
If the temperature outside is above 32 F then the roads are usually just mushy and slushy and not icy but you still need to be aware of some potential black ice that can still be on surfaces of the road.
You can't see that black ice because it's thinner and blends in with the color of the pavement.