By ESPNSTAR.com staff
Vettel currently leads the drivers' championship with Ferrari's Fernando Alonso just ten points behind.
In the most recent race in Abu Dhabi, the 25-year-old German raced superbly all the way from the pit lane to the chequered flag and grabbed hold of a third-placed finish to dash Alonso's hopes of catching up in the title race.
The performance earned him a number of plaudits from within the racing community and served to put notice that Vettel is not just the beneficiary of some world class engineering that has helped build a speed demon of an RB8.
But poor weather can often cause an upset and Vettel struggled in rain-soaked Sepang in the Malaysian Grand Prix in the earlier part of the season. On that occasion, Vettel had to pit late in the race following a clash with HRT's Narain Karthikeyan and could only secure a non-points finish while Alonso ended up as the winner.
Webber believes that rain, which is far more probable in Sao Paulo than in the upcoming United States Grand Prix next weekend, could wreck Vettel's chances of winning a third consecutive title.
"Sebastian needs dry weather there [in Interlagos]," the Australian told Austrian Servus TV.
"He can also drive in the rain, but Fernando is very strong.
"And it can be wet in Sao Paulo.
"In Sao Paulo there is always some drama."
Vettel secured pole position in qualifying in the 2011 edition of the Brazilian GP but lost out to Webber and had to settle for a second-place finish.