Apocalyptic movie, kind of?

There's this movie I saw a couple of years ago that, to this day, has had its scenes run through my mind. I don't remember the name but I believe the movie begins with an undercover cop and his partner in a car staking out a drug deal. Someone tips the drug dealers off and both the cops are under fire. His partner doesn't make it out alive but they manage to stop the dealers. The premise of the movie, from what I can remember, is that every day on earth starts getting hotter and hotter until it kills people. Eventually, the cop is one of the few still alive (he doesn't know this) and he tries to find other survivors. Could anyone possibly have any idea as to which movie I am talking about? Many thanks in advance to whoever helps me.