50F

50F (28C for most of the planet) is a really large temperature change. We've had several days of very cold temperatures here in Minnesota USA. It's been -20F/29C during the nights, slightly better during the days. I'm not kidding when I say that people here will be unzipping their coats and rolling down their car windows when the temperature soars to 30F/-1C eventually.

vocalista001 mentioned a new service from the weather underground with nice interactive temperature map. While scrolling around the planet on this map, I came to an important realization...

From our current position of -20F/29C here in Minnesota:
a drop of 50F/28C would get us to the equivalent of an average day on Mars, and
a rise of 50F/28C would get us to the current for-real warm summer day in Antarctica.