In situ high-temperature AFM was used to locally follow dynamic processes, leading to directed self-assembly of copolymers in the context of graphoepitaxy. We focused on the effect of heating for temperatures much higher than the T-g of the used PS-b-PMMA polymer. We showed that such conditions favors the block rearrangement, leading to very regular and perfectly aligned structures in limited times. The use of in situ AFM allowed us to locally investigate the self-organization process at high temperature, thus bringing new insights into self-assembly of block copolymers by graphoepitaxy. In particular, we demonstrate that a slight increase of temperature between 180 and 200 degrees C allowed overpassing an energy barrier and considerably improves the long distance arrangement, even for relatively short times.