changeable [ˈtʃeɪndʒəbl] - liable to unpredictable variation. “the weather will be changeable with rain at times”.
nasty [ˈnɑ:stɪ] - very bad or unpleasant. “plastic bags burn with a nasty, acrid smell”. comparison [kəmˈpærɪsn] - a consideration or estimate of the similarities or dissimilarities between two things or people. “they drew a comparison between Gandhi's teaching and that of other teachers”.
meteorological conditions - the prevailing environmental conditions as they influence the prediction of weather - the application of science and technology to predict the conditions of the atmosphere for a given location and time.