Defender Paul Quinn, making his first start for County, nodded in from a corner in the 11th minute before Adam Drury levelled two minutes before the break with a close-range header.
After the break Graham Carey restored County’s lead but the advantage only lasted two minutes before Buddies’ midfielder Jeroen Tesselaar equalised with a great strike on the hour.
With just two minutes played, St Mirren’s Kenny McLean had the ball in the visitor’s net following a corner but his effort was disallowed by referee Don Robertson for a push.
The home side threatened to dominate in the swirling wind and rain, but Quinn stunned them with a goal against the run of play when he headed home from a corner as the home defence went missing at the set-piece.
St Mirren pressed forward and County keeper Mark Brown was forced to made a great double save to first beat away Thomas Reilly’s volley and then palm out Callum Ball’s effort on the rebound.
Michael Gardyne thought he had doubled the visitors’ lead but his goal was disallowed for offside and St Mirren keeper Marian Kello did well to deny Jackson Irvine.
Drury (44) levelled just before the break as he got on the end of a long throw and nodded home after Ball had flicked the ball on.
Ball then had a great chance to put Saints in front but he failed to hit the target with the goal at his mercy and Gardyne was denied for a second time when his effort was disallowed once again by an offside flag.
Carey (58) restored County’s advantage when he fired in from 20 yards but the lead was short lived as Saints levelled for the second time when Tesselaar (60) accepted a pass from Drury before curling home from 20 yards high into the roof of the net.
The Paisley side looked the more likely to get the next goal and it almost came in the 70th minute when left-back Sean Kelly found McLean with a cross but his looped header cleared the bar.
In the final minute Carey came close to grabbing a dramatic winner when his long, wind-assisted free-kick beat Kello but hit the bar before going over.