Why does my swollen leg feel warm to the touch?

Two possibilities. Cellulitis is a deep skin infection which is very serious and needs to be addressed right away. It causes swelling warmth and pain and can cause sepsis. It is treated with antibiotics. The other cause is thrombophlebitis which is a clot in the deep veins of the leg. This is a medical emergency and needs prompts diagnosis and treatment. Both conditions can look identical. Get more tests!
Increased blood flow. Swelling with warmth means increased blood flow. Please have it evaluated as to the cause.

Related Questions

Hubby came home from work with a swollen leg from his ankle, to his knee, warm to the touch, and discolored. Ideas? He has no bug bites. Is overweight

See doctor. Have it evaluated right away, assuming no trauma, he is either suffering from a clot to the leg or an infection called cellulitis. Either way he needs prompt attention. Read more...
Might be blood clot. Uneven (l-to-r) swelling of an extremity with warmth & tenderness is very suspicious for a dvt. Should see your primary dr or go to er for evaluation so can begin treatment. Read more...
Swollen leg. The most likely diagnosis of cellulitis, and should be rapidly evaluated either at an urgent care Center, or emergency room. Often fungus from the toes can stimulate the cellulitis. Read more...

Why does a swollen leg sometimes feel warm?

Increased blood flow. Swollen leg can feel warm when cellulitis (infection of the soft tissues) is the cause. The inflammatory response to persistent swelling known as lipodermatosclerosis in venous disease is often painful and warm. Common denominator is vasodilation, relaxing of the vessel wall, resulting in increased blood flow, and hence the warmth. Read more...
Swollen leg. This is due to increase volume in the leg either blood or lymph fluid. Read more...