This thesis is a statistical study and analysis of hydrometeorological data and basic environmental variables on the island of Crete. Initially, the hydrological setting of Crete is presented, as well as the concept of statistical analysis and a detailed description of the methodologies used to analyze the hydrometeorological data.A general description of the study area is outlined, where it’s geological conditions are discussed, the key features of the climate with regard to environmental variables are presented, while reference is made to biodiversity of the island, on flora, fauna, and sensitive and protected areas. The description of the environmental database follows, which considers the space-time variations of the hydrometeorological variables on the island of Crete.Then, the statistical analysis of the aforementioned hydrometeorological variables is carried out. More specifically, the daily, monthly and annual cumulative rainfall is presented using descriptive statistics. The annual average of the total rainfall for the years 1974-2017, as well as the average of the dry and wet seasons are calculated, while its temporal variation is presented through descriptive charts. The rainfall recovery periods and the corresponding expected rainfall is determined using the periodogram and fitting of probability distributions. Similarly, analysis of evapotranspiration and effective rainfall occurs.Finally, the main conclusions are outlined concerning the spatial and temporal distribution of the hydrometeorological variables on the whole area of the island. More specifically, the following important conclusions were found:The West Coast shows a higher rainfall than the East and the rain increases with altitude. It was estimated that during the years 1974-2017, the rainfall variation followed a decreasing trend of 3mm/yr, while the average annual rainfall on the island of Crete accounts to 763, 61mm. It was estimated that 87% of the total rainfall of a hydrological year takes place during the wet period, while 13% corresponds to the dry season. For the prefectures of Chania and Rethymnon, it was estimated that the rainfall variation followed a decreasing trend of 4,8 mm/yr and 4,24 mm/yr respectively, while for the Prefectures of Heraklion and Lasithi, 2,62 mm/yr and 3,65 mm/yr, respectively. The highest rainfall is observed at Prasesses Station, which belongs to the prefecture of Chania, while the lowest rainfall is observed in Sitia, which belongs to Lasithi prefecture. Average monthly rainfall is peak in January or December and minimum in June and August, as well as at least 30% of annual rainfall in most stations of Crete, occur during the wettest months. Lastly, with regard to the evapotranspiration, the highest takes place in Plakias, while the highest effective rainfall in the prefecture of Cania. The year 2015 is the year with the highest evapotranspiration for the majority of stations, while the effective rainfall is highest mainly during December and January.