Depending on your setting, if you're making this a colder climate, fall isn't just cold, it's damp. If your character doesn't have a lot of very warm clothing and isn't in great shape, he or she is more than likely to have regular coughs, colds, bronchitic or flu-like illnesses, etc, especially if not able to afford proper food or have any way to cook it. He/she may wear some sort of soft cap or hat to bed as people did in previous centuries, in order to stay warmer.
Note: if there is an oven in the apartment, people who can't afford heat will often turn it on and leave the oven door open as a heater.
I can also tell you that in a house where the temperature is as low/high as 35-40 F--which it easily can be in the fall--it will still be unpleasantly, numbingly cold over any length of time. If you get hot food in a place like this, it will cool almost instantly. You can get fatigued just trying to stay warm, and if you become ill, it will be very difficult to get better.
Bottom line, people can survive in these conditions and many do, but they seldom thrive.