Minimum extreme temperatures over Peninsular Spain

Minimum winter extreme temperatures in 45 observatories distributed across Peninsular Spain have been analysed for the period 1955–1998. Extreme values have been defined locally from the 5 percentile of every minimum temperature distribution. Results reveal that most of the temperature extremes occur under six synoptic patterns. However, the role of synoptic processes is limited, providing favourable conditions for their occurrence, but not determining it completely. A generalised decreasing trend in the annual frequency of extreme events is detected for most of the studied observatories. Modelling through Poisson processes shows that it is due to a non-linear shift in the annual mean minimum temperatures associated to a generalised warming in the area.