We present a microscopic investigation of the temperature dependence of stripe domains in perpendicularly magnetized Ni films on Cu(001) using photoelectron emission microscopy in combination with x-ray magnetic circular dichroism (XMCD) in the resonant absorption of soft x rays. When the temperature approaches the Curie temperature of the system, the average width of the observed stripe domains is reduced along with the XMCD contrast. In addition, the domains become mobile. A quantitative analysis of the temperature-dependent motion of the domains yields an exponential behavior of the domain mobility with temperature, pointing toward thermally activated processes.