The old wives were wrong. Getting outdoors is a great idea when it's rainy and cold, say experts in infectious diseases.
As Sydneysiders endure the coldest start to a summer in 50 years, Peter Collignon, director of Infectious Diseases at the Australian National University, says the motherly advice - "don't go outside, you'll catch a cold" - is not only wrong, but potentially dangerous.
"While people think it's going out in the rain that makes you sick, it's actually the staying indoors," said Professor Collignon.
The reason more people get sick in winter isn't the weather conditions themselves, but how we react to them, says Professor Collignon.
The more people crowd indoors, the more infections they spread and the less vitamin D they get from the sun.
To highlight the message, another expert likes to tell his students about an experiment conducted in England many years ago.
"It was at the Common Cold Research Unit in Salisbury," said Professor David Isaacs, an infectious diseases expert at the University of Sydney.
"They [researchers] put them [volunteers] in an outdoor pool in England in the middle of winter with a rectal thermometer up their bottoms."
And what did they find?
"Getting cold doesn't give you a cold," Professor Isaacs said. "Stress and time of year, because you're crowded indoors, are much more important."
Miamii Hazell, of Maroubra, hasn't seen this research, but she's been raising her child as if she'd known it all along. Her 11-year-old son, Ethan, has asthma and chronic lung disease, and Ms Hazell said it was good for him to be outdoors in the cold and rain.
Ethan was splashing in the mud at Centennial Park with his friend, Eliane Sage, 8. Eliane's mother, Annette, said she was a passionate believer in all things wet, dirty and cold.
"I've got three kids," said Annette. "We go camping and they don't have showers for a week and they get wet and cold and they swim in the sea in winter and they go into dams in winter and they don't get sick.
"The people that sit at home and clean their houses with disinfectant all the time are the ones that have sick kids."