Vasoconstriction - blood vessels near the surface of the skin called arterioles constrict (become narrower) allowing less blood to the skin surface and therefore less heat is lost by radiation.

The inflammation affects the smaller vessels of the skin such as the capillaries and the medium-size vessels that include venules and arterioles. Small vessel vasculitis is the most common cause ...

This lowers the body temperature. Blood vessels called arterioles near the surface of the skin dilate (get wider) allowing more blood to the skin surface where more heat can be lost by radiation.