If you live in Spain, you may have felt like some weather occurred on a predictable cycle, even a weekly one. And if you are below a certain age, you may even have been planning your seasonal activities around it your whole life.

You aren't alone. Arturo Sanchez-Lorenzo of the University of Barcelona and colleagues from the University of Girona, the University of Valencia and the University of Augsburg have thought the same thing.

Writing in Geophysical Research Letters, they detail their study of Spain during the 1961–2004 period. To minimize the impact of local variables, they used 13 series from stations placed in different climatological and geographical areas.

What they found was that there were cycles and those even had seasonal shifts. In the winter there was more rain during the week, in the summer it was (unfortunately) almost the opposite.

These 'hebdomadal' cycles, they say, are related to the atmospheric circulation all over western Europe and not just local smog - but the climate issues for western Europe are related to anthropogenic aerosols.

Citation: Sanchez-Lorenzo, A., J. Calbó, J. Martin-Vide, A. Garcia-Manuel, G. García-Soriano, and C. Beck (2008), Winter “weekend effect” in southern Europe and its connections with periodicities in atmospheric dynamics, Geophys. Res. Lett., 35, L15711, doi:10.1029/2008GL034160.