Cats go into heat as often as every two to three weeks during their active breeding season, which generally runs from early spring (around February or March) until autumn (around October or November). These cycles can repeat multiple times throughout this period if the cat does not mate. Each heat cycle usually lasts about 7 to 10 days, though it can range from 3 to 14 days. Indoor cats with artificial lighting may experience heat cycles year-round. The first heat for female cats typically occurs between 4 to 12 months of age, sometimes as early as 3 to 4 months depending on breed and environmental factors.