Swelling in the ankles, feet, or legs is frequently brought on by fluid buildup, also known as oedema. This happens when extra fluid leaks from blood vessels and accumulates within the bordering tissues. Some popular causes of swollen ankles and feet include: Very hot weather could also cause heat edema. https://www.sgvascularctr.com/swollen-leg-why-do-i-have-it-and-what-can-i-do/