Cat heat, called estrus, lasts between 3 and 14 days. The average length of time is one week. If a female cat doesn’t become pregnant, the cycle repeats every two to three weeks.
When a female cat goes into heat, it means that they are ready to have litters of kittens. If the cat mates while in heat and becomes pregnant, the pregnancy lasts 60 to 64 days on average before giving birth. If the cat mates and doesn’t get pregnant, it may take up to 30 days before the cat goes back in heat again. If a female cat isn’t spayed, the cycle continues in this vein until the cat has kittens. Generally this happens during mating season which often happens during the spring, but a cat may go into heat during any season. When in heat, female cats often become extra friendly toward people and other cats. They might rub against the legs of people or roll on the floor in front of them. They might weave in and out of the legs of visitors as well. Because female cats only ovulate when they mate, and they can mate more than once for multiple ovulations, more than one cat can sire a litter.