Arsenal stopper Szczesny expects Hart to bounce back after being benched by Manuel Pellegrini for the club's last four fixtures.
The England number one, 26, paid the price for a poor run of form after another high-profile mistake in the 2-1 Premier League defeat at Chelsea, with Costel Pantilimon replacing him.
Szczesny, who shares the same agent with friend Hart, experienced a similar situation last season when Arsene Wenger preferred Lukasz Fabianski for five games in March and April.
The 23-year-old won his place back from his fellow Poland international, however, and he is tipping Hart to do the same.
"I rate Hart as one of the best, if not the best, goalkeepers in the world," said Szczesny.
"Over the last couple of years, he was the most consistent. But age has this thing where you are not as consistent as an older goalkeeper.
"Forget the last couple of weeks, where it has been very difficult for him and he has been dropped. Everybody has got to go through that.
"When you're out of the team, you have time to sort things out. It is very important to relax and maybe have a bit of time away from the pressure, getting the right mindset.
"It seems to be working for me, and I definitely hope that Joe will do the same. If he comes back stronger, it is scary to think how good he is going to be."