||The work deals with the empirical research of informal institutions. The aim was to determine on the basis of the verification of weather lores whether our null hypothesis is valid. Our null hypothesis is as follows: known weather lores have a higher success rate of forecast than unknown weather lores. We worked on the assumption, that in the general awareness remain mainly weather lores that works (passed on from generation to generation as a result of long-term learning process). That should have clarified whether not working weather lores are used any more. We verified weather lores on the basis of hydro-meteorological data for the period 1972-2002. We used several measure criteria. Each criteria was tested with Student's t-test. For all criteria, we observed that at the 5% level of significance we could not reject the hypothesis of equal values of known and unknown weather lores. It was not confirmed our hypothesis that known weather lores have a higher success rate of predictions. That means there is no development of informal institutions in the context of informal institutions on the basis of our empirical research.