Drug user Kelly Langham, 26, returned to her car just as police officers arrived. They had been called by a member of the public after the sweltering children frantically sounded the horn.
Ms Langham claimed she had only intended to leave them for five minutes as she visited a 'Cash Converters' store, but had encountered a three-quarters of an hour long queue.
Pleading guilty to wilful neglect Langham admitted she had earlier taken amphetamines and that her thinking was 'not as it should have been'.
The magistrates heard that a little girl was found to be "crying, red in the face and distressed" when horrified passer-by James Sanderson alerted the police. He said: "In the rear was a child in a car seat screaming and crying."
A police officer who raced to the scene in Carlisle city centre told the court "The heat was so high it would have been dangerous and potentially harmful to the children in the car."
The children are now being cared for by a relative.
Bailing Langham until August 1st, magistrates' chairman Nick Swinscoe told her: "This is a case we think we need much more background knowledge on. We need a full report. We are not going to rule out custody."
In May we brought you this horrifying story of a toddler who died after being left in a baking hot car.