Weather data could help predict up to three days in advance when the number of out-of-hospital cardiac arrests is likely to rise above average, according to a nationwide study of more than 114,000 cases by researchers. The study found that lower temperatures emerged as one of the most important weather-related risk factors examined. In the future, models based on weather forecasts could help people with cardiovascular disease and their families prepare for higher-risk periods, while also supporting ambulance services and hospitals in managing expected increases in demand.