When we experience hot weather in the UK, we're not usually that prepared for the effect it can have on our bodies, such as heat oedema.
This is when you might experience swelling or puffiness in the ankles, feet and legs, often caused by a build up of fluid in these areas, more generally called oedema.
But when temperature rises, blood vessels near the surface of your skin automatically widen as a way of keeping your body cool. This increased blood flow can cause clear fluid from your lymph system (part of the immune system, and complementary to the circulatory system) to leak into the surrounding tissues, causing the swelling.
Some people naturally have more leaky capillaries (delicate blood vessels) than others, and most people will find this leakiness tends to increase with age.
Read more: Hot weather: Why you shouldn't sleep naked
While it's perfectly normal to have some swelling in the heat, especially in your lower limbs, a large amount of fluid build-up or swelling for no reason could be a sign of an underlying health condition, or the heat could be making something pre-existing worse. It's always wise to check this with your doctor.
Normal swelling should go away on its own, but there are some things you can do to try to help ease the discomfort in your sandals.