Falkirk lost from a dominant position to fall six points off the top of the SPFL Championship.
The Bairns were in complete control in the first half, but failed to make their dominance pay in goals.
They still entered the break a goal up thanks to Rory Loy’s lifted strike from a Mark Beck flick-on.
But in the second half Mitch Megginson glanced in a header and Jordan Kirkpatrick struck the winner past Michael McGovern to continue the home side’s run of good form, and inflict the Bairns’ second consecutive defeat.
Falkirk had named an attacking line-up which included Mark Beck, in at the expense of the injured Blair Alston. The loanee from Carlisle put in an excellent performance, but was one of a number on top of their game in the first half when Falkirk had the wind at their backs.
After sizing up Stephen Grindlay the Bairns took the lead when a Stephen Kingsley long ball was nodded on to Rory Loy. He had found space and beat the goalkeeper to the ball at the edge of the box and steered it into the net.
Beck could have made it two with a header that Mark Gilhaney blocked on the line and though the 6’5” Bairns followed it up he couldn’t bundle the ball in and it sneaked past the post.
Phil Roberts was ijhn fine form for the first half and linked well and supplied a number of crosses, but none could add to the Bairns advantage.
Dumbarton had attacked only a handful of times and though they did look dangerous, the infrequency of the threat gave Falkirk a real dominance. However it was a complete role reversal in the seocnd half with the team with the wind behind them exerting authroity in the second half.
Falkirk’s dominance vanished and the link-up in attack disintegrated. Ideas ran out and Dumbarton pressed with the weather advantage. The equaliser still came against the run of play when Megginson glanced in a cross from Colin Nish.
Immediately Dumbarton sensed blood and attacked with confidence and Falkirk were soon behind when a Jordan Kirkpatrick strike seemed to catch Michael McGovern out - possibly unsighted - and sneaked inside the post.
The Bairns pushed for the equaliser of their own, but Craig Sibbald’s shot from Kieran Duffie’s cut-back was weak and Rory Loy’s follow-up squirmed wide.