Print a temperature calibration tower to determine the flow characteristics of your filament (https://www.thingiverse.com/thing:1298948).
I do this for every new spool. And repeat it when things go weird (such as due to the arrival of cooler weather). The key thing to know is that neither the "actual" temperature of the nozzle nor the "indicated" temperature matter at all! What matters is that the filament prints well (whatever setting is needed), and the tower makes that happen. In the case of my crappy 101Hero, the hot-end temperature indication was way off, and the firmware wasn't released so I couldn't update the conversion constant, but I get great prints working from the temperature tower.
I also do a speed calibration tower (https://www.thingiverse.com/thing:1381839) whenever mechanical issues arise (which can also be due to ambient temperature changes).
I keep an old install of Cura 15.04.6 around just for printing these towers, so I can avoid affecting other projects. I print the towers using "draft mode" (high speed, thick layers), since printing slower with thinner layers can hide some issues. Also be sure to slice with no more than two bottom layers, single wall, no fill, and no top layers, to make the prints as fast as possible.