  The flagship measurement of the JUNO experiment is the determination of the
neutrino mass ordering. Here we revisit its prospects to make this
determination by 2030, using the current global knowledge of the relevant
neutrino parameters as well as current information on the reactor configuration
and the critical parameters of the JUNO detector. We pay particular attention
to the non-linear detector energy response. Using the measurement of
$\theta_{13}$ from Daya Bay, but without information from other experiments, we
estimate the probability of JUNO determining the neutrino mass ordering at
$\ge$ 3$\sigma$ to be 31% by 2030. As this probability is particularly
sensitive to the true values of the oscillation parameters, especially $\Delta
m^2_{21}$, JUNO's improved measurements of $\sin^2 \theta_{12}$, $\Delta
m^2_{21}$ and $|\Delta m^2_{ee}|$, obtained after a couple of years of
operation, will allow an updated estimate of the probability that JUNO alone
can determine the neutrino mass ordering by the end of the decade. Combining
JUNO's measurement of $|\Delta m^2_{ee}|$ with other experiments in a global
fit will most likely lead to an earlier determination of the mass ordering.
