-40 is -40, but -120 celsius is -184 Fahrenheit.
The Martian equatorial regions' ground temps can reach the 60s Fahrenheit.
The polar regions in their winters can get as cold (ground temp) as -220 F.
The mean surface temperature on Mars (and it's mean all right!) is around -80 F.
The thin atmosphere cannot hold much heat; it's always colder than the surface.
Here's a graphic from the Mars Pathfinder mission of 5 1/2 years ago:
Pathfinder's location is about 19.33 N, 33.55 W.
A "Sol" is a Martian day, about 24.65 Earth hours.
Kelvin is the Celsius scale measured from absolute zero. Just subtract 273 from any Kelvin temp for the Celsius equivalent. Then convert to Fahrenheit with the following formula: X times 9 divided by 5 plus 32.