How bright is Mars?
The current visual magnitude of Mars is -2.17. Given its brightness, Mars should be visible to the naked eye, easyly even from highly light polluted areas.
The following chart is the predicted light curve (visual magnitude as a function of time) of Mars, according to the most recent ephemerides data. Magnitude data is sampled with a 2 days interval and there might be inaccuracies for objects changing brightness very rapidly during the course of a few days. For comets there could be large discrepancies between the observed and predicted brightness because of their highly dynamic behaviour.
Predicted magnitude of Mars between
January 1900 and January 2100