Jashore had the previous highest temperature of the season at 42.6C
The fire incident caused the EC damage worth over Tk 37.7 million, the committee has confirmed.
The affected place was used to keep electronic voting machines or EVMs.
Inspection of the site, accounts of witnesses and firefighters, and CCTV camera footage pointed to electric short-circuit as the reason behind the fire on Sunday night, Mokhlesur, who headed the four-member committee, said.
The materials damaged in the fire include 59 EVM control units, 47 batteries, 789 ballots, 1,233 monitors, and nine air-conditioners, coverings of floors, walls and ceilings.