what's the coldest it's ever gotten on neptune?
The mean atmospheric temperature on Neptune is as low as â218 Â°C (55.1 K) at the cloud tops and about -200 Â°C (72 K) at the pressure level equal to 1 Earth atmosphere. The lowest observed temperature within the atmosphere is about -221Â°C (51.8 K). Probably something like -210 degrees celcius but no one knows the exact temperature.