Yes, you need line of sight at the beginning of your turn to charge an opponent.
Round 592
As the invisible 20cc enters the Victory Zone, he ignores the flames (18 CL check), but cannot ignore the choking cloud of smoke that emanates from the wall of fire (at 80N60E) just as he enters the Victory Zone, although 20cc is not choking (32+2=34 Fort save). Neither combatant can see the other, although each can blindsense the other.
20cc misses because of the smoke.