Cold ambient temperatures lead to a heightened risk of the most lethal form of stroke, say researchers.
Comfort's not the only reason to rug up when the temperature plummets - cold weather has been found to increase the risk of stroke.
Cold ambient temperature leads to a heightened risk of the most lethal form of stroke, intracerebral haemorrhage (ICH), say The George Institute for Global Health researchers.
Their study, published in PLOS One, involved 1997 patients globally between 2008 and 2012 and found almost 80 per cent of strokes occurred below 20C.
Using 20 as their optimal reference temperature, they found the odds of experiencing ICH were 1.37 times higher at 10C, 1.92 higher at zero, 3.13 higher at minus 10 and 5.76 higher for minus 20.
They also discovered ICH was more likely to occur in the first two to three hours of exposure to cold temperatures.
Chief author, PhD student Danni Zheng from the Institute's Australian division, told AAP the study used hourly temperatures, while previous research used monthly or daily temperatures.
About seventy per cent of the patients had a known history of suffering high blood pressure.
Previous studies hypothesised that cold temperatures may trigger ICH through the narrowing of blood vessels and elevations in blood pressure.
Ms Zheng said the issue was of most concern to people in countries with sub-zero temperatures, such as China and Canada.
"ICH is a devastating disease with high mortality and morbidity rates.
"In 2010 alone there were 5.3 million new cases of ICH and over 3 million deaths from ICH worldwide."
According to the Stroke Foundation, there are around 50,000 new and recurrent strokes each year in Australia with ICH accounting for about 7500 of them.
"The risk of ICH in high-risk subjects might be reduced by more stringent monitoring and management of blood pressure levels during cold season," the researchers said.
Other action could include "targeted person advice and environmental heating interventions, triggered by forecasts of very low temperature".