The purpose of this paper is to study hourly time series of temperature and humidity from six meteorological stations in Oman from 2009 to 2018. Since our data contains missing values due to device failures, we have compared several methods of imputation and found that regression with lagging is most reasonable. To extract the annual oscillations and daily periodicities from hourly time series we apply Singular Spectrum Analysis. By applying the Mann–Kendall test, Spearman’s rho test and the ITM test to the annual oscillations and daily periodicities monotonic trends in temperature and humidity over the ten year period have not been confirmed.