Sometime between 2009 and 2016,Mars got hit by a cosmic shotgun.
A small asteroid or piece of comet, probably not more than a couple of meter across, or entered the atmosphere of Mars at high speed. As it did,it rammed the air in front of it at hypersonic velocities, compressing it mightily. When you compress a gas it heats up, or when you compress it with something moving dozens of kilometers per moment it heats up a lot.
Source: blastr.com