If you are an iPhone user, the weather is always a particularly nice 70 degrees. Or 68 degrees. But if the temperature is 69 that is too hot for Apple fanboys.
The built-in weather app on some versions of iOS -- including the current version, iOS 14.6 -- will refuse to display the number, even if the actual temperature in a given location is, in fact, 69 degrees.
It's not clear if this is a bug or an intentional attempt from Apple to censor any immorality amongst is users. The last thing Apple wants is American mothers ringing up the spaceship claiming that their precious snowflake has been lead down the path to drug use, satanism, homosexuality, liberalism, feminism and dungeons and dragons by Apple’s immoral weather app with its erotic numbers.
The rounding is only visible in the weather app itself: clicking through to Apple's source data from Weather.com will show the proper temperature, as does Apple's home screen widgets.
We guess it is because you would have the immoral number in your hand which makes it dangerous.