"It is a reward for the extremely positive start he has made to his Brentford career," said manager Andy Scott.
"I have been delighted with his input and improvement during the comparatively short time he has been with us and have every reason to believe he will improve still further, add to his goal tally and continue to be a force for Brentford."
Weston scored twice in Saturday's 4-0 win over Gillingham to take his tally for the season to nine.
Meanwhile, Bees defender Tommy Smith, who is on loan from Ipswich, has been provisionally called up into the New Zealand squad for a friendly against Mexico in Los Angeles next month.
Source: Team Talk
Source: Team Talk