There were more heart attacks on days when the temperature dropped below freezing and fewer when it rose above 39 degrees Fahrenheit. With each increase of 13 degrees Fahrenheit, heart attack risk dropped by 2.8 percent.In discussing the weather-heart attack connection, study leader David Erlinge, a professor of cardiology, said cold and windy weather “leads to a contraction of blood vessels in the skin to conserve energy,” which increases the workload of the heart. Other factors that may be involved are alterations in behavior that occur on cold winter days, such as changes in diet or exercise habits. Colds and flu, which are more common in winter, also have been linked to increased risk. The researchers cited a 2018 study showing a six-fold increase in heart attacks within seven days after the onset of the flu and a smaller increase in risk within a week of a cold. Dr. Erlinge also noted that cold, windy weather increases emotional stress, which is another risk factor. The study didn’t explore whether avoiding cold temperatures by staying indoors or wearing warm clothes could reduce the risk. Dr. Erlinge did say that people at high risk of heart attack “may want to avoid going out in cold, windy weather.”The American Heart Association warns that people with coronary heart disease often suffer chest pain or discomfort (angina pectoris) in cold weather. It suggests wearing layers of clothing as well as a hat or head scarf, and to keep your hands and feet warm. If you’re shoveling snow, the AHA cautions against drinking alcohol before or afterward – it can give a false sensation of warmth and cause you to underestimate the extra strain on your body.