  We revise cosmological mass bounds on axions in low-reheating cosmological
scenarios, with a reheating temperature $T_{\rm RH}\le 100$ MeV, in light of
the latest cosmological observations. In this situation, the neutrino
decoupling would be unaffected, while the thermal axion relic abundance is
suppressed. Moreover, axions are colder in low-reheating temperature scenarios,
so that bounds on their abundance are possibly loosened. As a consequence of
these two facts, cosmological mass limits on axions are relaxed. Using
state-of-the-art cosmological data and characterizing axion-pion interactions
at the leading order in chiral perturbation theory, we find in the standard
case an axion mass bound $m_a < 0.26$ eV. However, axions with masses $m_a
\simeq 1$ eV, or heavier, would be allowed for reheating temperatures $T_{\rm
RH} \lesssim 80$ MeV. Multi-eV axions would be outside the mass sensitivity of
current and planned solar axion helioscopes and would demand new experimental
approaches to be detected.
