"I don't think they can, because the weather has to be so specific," Pattinson said.
A sequel may get the green light this month, he said.
"They will literally decide the next day or the day after" once the movie opens, Pattinson said. "I think they only have plans to do the second one. There's no script for the third one. The script is already done for the second one."
Pattinson also talked about why 108-year-old Edward Cullen—the Chicago-born vampire he plays in the film—is attracted to teenage love interest Bella Swan.
"Initially, it's just the smell of her blood," said Pattinson, 22. "She has a weird blood type. And he stopped killing people 50, 60 years ago. She breaks down all his discipline, immediately. He thinks, 'I'm not going to let 50, 60 years of work get destroyed by this insignificant girl.' So, he starts testing himself. And he starts to fall for her."
In the book, Edward is represented as a perfect gentleman and the ideal man. How difficult was it for Pattinson to play a perfect character?
"I just kind of ignored it," Pattinson said. "I just tried to concentrate on his flaws. I can do the flaws and forget about the rest."