Woods, who is taking an indefinite break from the sport, has been in hiding since admitting last month he had cheated on his wife.
"Those who say he won't play again are crazy," Harmon said in an interview with Sky Sports on Friday.
"People who say he probably won't play this year, I don't really believe that (either). If you want to put a timetable on it, I'd say you may see him in Florida before the U.S. Masters (in April)."
Woods generally plays in the WGC-CA and Arnold Palmer tournaments.
Harmon, who commentates for Sky, said the main reason he believed the 14 times major winner will compete in 2010 is that the U.S. and British Opens are being played on courses Woods likes.
"Pebble Beach and St Andrews are two of his favorite places so I think he will come back and play there," said the American who now coaches world number two Phil Mickelson.
Harmon said the revelations about Woods's private life had come as a complete surprise.
"This Tiger Woods I'm reading about, I don't know who this guy is," he said. "Obviously, he has led two lives -- one in public and one we didn't know about which was quite strange.
"I think all of us were a little shocked about that. We don't know where Tiger is right now or what he is doing. I just know we (in golf) miss him."
(Writing by Tony Jimenez; Editing by Ken Ferris)