January
First of all as it says in the table the tempurature in january is -11.6 and decembers tempurature is -10.4. next i checked that -11.6 is lower or colder than -10.4 by seeing that when you minus some from -10.4 it would equal to -11.6 meaning that -11.6 is lower or colder than -10.4. Last that is why january is colder than december and that is how i got my answer.