This adult pipistrelle was seen flying around a storeroom by startled members of staff at the Millets outdoor store in Halifax.
It has been rescued by Hugh Firman, the chairman of the West Yorkshire Bat Group, whose colleagues have taken in around 70 bats this winter.
Bats waking from hibernation require human help to survive because there are few insects to eat and an average bat gets through 3,000 midges in a single day.
Mr Firman believes the spell of extremely cold weather, coupled with the heating being turned up in buildings where bats are roosting, may account for an increase in the numbers of bats waking early.
Extreme cold may awaken some and others may think spring has arrived if they are in a well-heated building.
Mr Firman, who works for Calderdale Council as a conservation officer, said: "This bat seems to be fine; it has a very big appetite. It took it a while to get it used to meal worms, which are not its usual food."