  Low-mass galaxies are highly susceptible to environmental effects that can
efficiently quench star formation. We explore the role of ram pressure in
quenching low-mass galaxies ($M_{*}\sim10^{5-9}\,\rm{M}_{\odot}$) within 2 Mpc
of Milky Way (MW) hosts using the FIRE-2 simulations. Ram pressure is highly
variable across different environments, within individual MW haloes, and for
individual low-mass galaxies over time. The impulsiveness of ram pressure --
the maximum ram pressure scaled to the integrated ram pressure prior to
quenching -- correlates with whether a galaxy is quiescent or star-forming. The
time-scale between maximum ram pressure and quenching is anticorrelated with
impulsiveness, such that high impulsiveness corresponds to quenching
time-scales $<1$ Gyr. Galaxies in low-mass groups
($M_\mathrm{*,host}\sim10^{7-9}\,\rm{M}_{\odot}$) outside of MW haloes
experience typical ram pressure only slightly lower than ram pressure on MW
satellites, helping to explain effective quenching via group pre-processing.
Ram pressure on MW satellites rises sharply with decreasing distance to the
host, and, at a fixed physical distance, more recent pericentre passages are
typically associated with higher ram pressure because of greater gas density in
the inner host halo at late times. Furthermore, the ram pressure and gas
density in the inner regions of Local Group-like paired host haloes is higher
at small angles off the host galaxy disc compared to isolated hosts. The
quiescent fraction of satellites within these low-latitude regions is also
elevated in the simulations and observations, signaling possible anisotropic
quenching via ram pressure around MW-mass hosts.
