It could be lymph congestion causing edema (fluid retension) in your extremeties. The best way to attack it is through rebounding -- jumping on a mini trampoline for 10 mins, 3x daily. Since it is tied to temperature, try alternating hot/cold showers. 1 min as hot as you can take it, 1 min stone cold, repeat. Gradually work up to 3 minute cycles. This is very stimulating to the lymph system.
Another possibility is to increase dietary potassium, in the event your salt/potassium balance is off and the excess salt is causing swelling. High blood pressure is another symptom of low potassium.
Get potassium by eating fish (salmon, cod, flounder, and sardines), vegetables (broccoli, peas, lima beans, tomatoes, potato skins, and leafy green vegetables), fruits (citrus, apples, bananas, and apricots). Dried apricots contain more potassium than fresh apricots and they are available year round.