  In this paper, we analyze several instrumental records of temperatures at
different locations by using new techniques originally developed for the
analysis of extreme values of dynamical systems. We show that they have the
same recurrence time statistics as a chaotic dynamical system perturbed with
dynamical noise and by instrument errors. The technique provides a criterion to
discriminate whether the recurrence of a certain temperature belongs to the
normal variability or can be considered as a genuine extreme event with respect
to a specific timescale fixed as parameter. The method gives a self-consistent
estimation of the convergence of the statistics of recurrences toward the
theoretical extreme value laws.
