She sustained the injury after her convoy car abruptly halted due to poor visibility on the highway.
Banerjee had gone to the district headquarters Bardhaman town for an administrative meeting.
She was scheduled to return by helicopter, which did not fly due to drizzle and poor visibility owing to foggy conditions.
The Trinamool Congress chairperson suffered minor injuries on her head and was being brought back to Kolkata, the sources added.
