The large amounts of data from molecular biology and neuroscience have lead
to a renewed interest in the inverse Ising problem: how to reconstruct
parameters of the Ising model (couplings between spins and external fields)
from a number of spin configurations sampled from the Boltzmann measure. To
invert the relationship between model parameters and observables
(magnetisations and correlations) mean-field approximations are often used,
allowing to determine model parameters from data. However, all known mean-field
methods fail at low temperatures with the emergence of multiple thermodynamic
states. Here we show how clustering spin configurations can approximate these
thermodynamic states, and how mean-field methods applied to thermodynamic
states allow an efficient reconstruction of Ising models also at low
temperatures