  Commensurate and incommensurate antiferromagnetic fluctuations in the
two-dimensional repulsive t-t'-Hubbard model are investigated using functional
renormalization group equations. For a sufficient deviation from half filling
we establish the existence of local incommensurate order below a pseudocritical
temperature T_{pc}. Fluctuations not accounted for in the mean field
approximation are important--they lower T_{pc} by a factor \approx2.5.
