  We model the 21cm power spectrum across the Cosmic Dawn and the Epoch of
Reionization (EoR) in fuzzy dark matter (FDM) cosmologies. The suppression of
small mass halos in FDM models leads to a delay in the onset redshift of these
epochs relative to cold dark matter (CDM) scenarios. This strongly impacts the
21cm power spectrum and its redshift evolution. The 21cm power spectrum at a
given stage of the EoR/Cosmic Dawn process is also modified: in general, the
amplitude of 21cm fluctuations is boosted by the enhanced bias factor of galaxy
hosting halos in FDM. We forecast the prospects for discriminating between CDM
and FDM with upcoming power spectrum measurements from HERA, accounting for
degeneracies between astrophysical parameters and dark matter properties. If
FDM constitutes the entirety of the dark matter and the FDM particle mass is
10-21eV, HERA can determine the mass to within 20 percent at 2-sigma
confidence.
