The 29-year-old was pipped to the victory by Japan’s Daiki Ito with the last jump of the competition in Finland.
Ito’s points total of 245.5 was enough for his third win of the season while Bardal was 6.3 points behind and Czech Lukas Hlava completed the podium.
Bardal's nearest rival Gregor Schlierenzauer could only manage sixth in Lahti.
Heading to Finland Bardal held a 44 point advantage over Schlierenzauer but that has now been extended to 84 with four rounds remaining.
And sixth-placed Ito has now given himself a chance of finishing the season in the top three as third-placed Andreas Kofler could only manage 25th, fourth-placed Kamil Stoch finished 39th and fifth-placed Thomas Morgenstern was seventh.