  Context. As a new growing field, exocartography aims to map the surface
features of exoplanets that are beyond the resolution of traditional observing
techniques. While photometric approaches have been discussed extensively,
polarimetry has received less attention despite its promising prospects.
  Aims. We demonstrate that the limb polarization of an exoplanetary atmosphere
offers valuable insights into its cloud cover distribution. Specifically, we
determine an upper limit for the polarimetric precision, which is required to
extract information about the latitudinal cloud cover of temperate Jovian
planets for scenarios of observations with and without host stars.
  Methods. To compute the scattered stellar radiation of an exoplanetary
atmosphere and to study the polarization at various planetary phase angles, we
used the three-dimensional Monte Carlo radiative transfer code POLARIS.
  Results. When the planetary signal can be measured separately from the
stellar radiation, information about the latitudinal cloud cover for polar cap
models is accessible at polarimetric sensitivities of $0.1$ %. In contrast, a
precision of about $10^{-3}$ ppm is required when the stellar flux is included
to gain this information.
