A two-goal assalt by Junior Agogo destroyed Kidderminster after their coach had been held up on the motorway.
The Rovers' striker could have ended with four or five but for a brilliant performance in Harriers goal by John Danby.
Defensively it was a bad day for them and late on they were lucky to survive two clear- looking penalty appeals.
After arriving late, Kidderminister found themselves being hustled from the start by a buoyant home side.
Their cause was not helped midway through the first half when Danby went over on his left ankle and skipper Wayne Hatswell had to take goal kicks.
Rovers went ahead after 21 minutes. Their front pair of Richard Walker and Agogo had not been timing their runs and passes on the wet surface, but everything fell into place with a Walker head flick.
Agogo beat the off side line, side-stepped Danby's desperate rush off his line and steered his ninth goal of the season into the net.
He soon had the ball in the net again but this time the flag was up as Rovers stayed on top.
While Agogo was a menace in attack, Rovers relied heavily in defence on Christian Edwards as Harriers tried to shake off their record as the lowest scorers in the division. Their best chance came when Dean Keates split the home defence with a pass to James Keene running through on his left.
An equaliser looked certain but they had to settle for a corner as ex-Harrier Craig Hinton dived in with a saving tackle. Danby kept Harriers in the game with a string of good stops in the second half as his defence struggled.
Then a long run by Lee Thorpe, who had replaced Walker, led to Rovers going further ahead. He squared the ball for Agogo to run in his second before the ebullient striker went off to a standing ovation.