The intra- and inter-variability observed with regard to the extent, duration and severity of psoriasis is the result of the interaction of genetic and environmental factors. In clinical practice, once efficacy has been achieved with anti-Tumor Necrosis Factor (TNF) drugs, temporary suspension of such treatment is followed by a disease-free period. To date, the factors that condition the differences in the duration of remission obtained in clinical setting are not well understood. One of the environmental factors that might modulate the clinical expression of psoriasis is seasonal changes.2 Seasonal variations in solar radiation, degree of humidity or temperature may have a biological effect on the skin3-5 and immune system.6, 7