At low is antifreeze really rated?

"Wind chill does not apply to inanimate objects. They are always at ambient temp no matter how fast the wind blows. " - euryale1

“As others pointed out…Windchill does NOT effect how cold something will get…only the rate at which something cools.” MikeInNH

Just for the sake of argument, this isn’t totally true. Wind-chill is a meteorologist term for the effect that wind has on skin, but wind can affect the temperature of inanimate objects as well. At freezing temperatures and below, as discussed here, it is a non issue, but at higher temperatures, wind or air flow can cool an object below ambient.

In the past, water was poured over a metal grate with tube of water in it. The air flow from the wind or a fan would cool the metal grates and tubing full of water below ambient through evaporative cooling. The water in the tubes would be piped into a building to a hat exchanger to cool the building. This type of air conditioning is known as “swamp water coolers”. They are still in use in many older buildings, we have on at the factory where I work in the hot humid south.

Anyway, none of this applies to the original post, we aren’t using the swamp water cooler this time of the year and it becomes less efficient at lower temperatures. At 32F and below, water doesn’t evaporate fast enough to provide any significant cooling, no matter how fast the wind blows.