When do mares ovulate in their heat cycle?

In the cold months many mares show no signs of heat. But as the days grow longer and the temperature climbs mares have more obvious signs of heat. Every mare is different but they have a cycle about once every 4 to 6 weeks on average. Some mares have cycles closer together, some not as often. If the mare is bred and becomes pregnant she will have no more heat cycles until what is called 'foal heat' after her foal is born.