There is a need for good sun protection.
Avoid exposing the affected limb to the hot sun in the summer!
High temperatures can make blood vessels and lymphatic vessels dilate and inter-tissue lymphatic fluid exudation increase, especially in people at high risk for lymphedema, which can easily trigger or worsen lymphedema.
Use sunscreen, umbrellas, sun protection clothing, sun protection caps in the sun, or cover the affected arm with a gauze, and keep a small spray bottle on hand if necessary, so that when the skin temperature of the affected limb is too high, it is promptly sprayed locally to cool it down.