The olive tree is a significant woody crop in the Mediterranean basin, with the primary olive-growing areas located in the south and southwest of the Iberian Peninsula. Climate plays a crucial role in crop distribution, viability, production, and yield. The climatic and topographical conditions of Extremadura in southwestern Spain, were analysed to characterise and group the olive-growing areas. To achieve this, a Geographic Information System (GIS) was developed to locate all registered olive tree plots. The orientations and elevations of these were analysed, along with the average, minimum, and maximum temperatures, precipitation, and frost for the period of 1990–2021. The study reveals that olive groves in Extremadura are primarily situated at elevations ranging from 200 to 600 m above sea level. Additionally, it was found that the least common orientation is towards the north. Temperatures are not a constraint for olive growing, except in the mountainous areas in the north of the region; however, rainfall can be a limiting factor. In fact, 50% of the olive-growing area receives less rainfall than is considered adequate for optimal production. Frost days and the low probability of severe frosts are not a problem for olive growing in this region, except in the highest parts of the region. The scale of this study, at plantation level, will enable the implementation of measures aimed at climate change adaptation and mitigation.

The increasing variability of precipitation, higher temperatures, and recurring droughts in the semi-arid regions due to climate change are leading to increased aridity, resulting in scarcer water resources for crops. The present study aimed to analyse the spatial distribution of climate variables related to water resources in the olive-growing areas throughout Extremadura, southwestern Spain. To perform this task, three climate variables were used: the potential evapotranspiration of the crop, the FAO aridity index, and the annual water requirement. Considering data from 58 weather stations located throughout Extremadura and 17 along boundaries with at least a 30-year length (within the 1991–2021 period), each variable was computed at each station. After calculating some descriptive statistics, a multivariate geostatistical (regression-kriging) algorithm, incorporating secondary information on elevation and latitude, was used to accurately map each climate variable. Later, temporal trends and their magnitude were analysed using the Mann–Kendall test and the Sen’s estimator, respectively. The highest evapotranspiration and water requirements are located in the southern part of the region, which has large areas dedicated to olive cultivation. In the northern part of the region, there is greater spatial variability in evapotranspiration and, consequently, in water requirements for olive groves due to the more rugged topography. Similarly, the olive-growing areas with the highest aridity are also in the south of Extremadura. In most areas of Extremadura, olive cultivation requires appropriate irrigation for optimal productivity. According to evapotranspiration trends, the water requirements will become greater in the future. However, it is not guaranteed that the water supply will be sufficient in olive-growing areas where aridity is higher and water resources are scarce. The results of this study are very important for evaluating water deficit and water resources in vulnerable olive-growing areas throughout Extremadura.

The increasing variability of precipitation, higher temperatures and recurring droughts in the semi-arid regions due to climate change are leading to increased aridity, resulting in scarcer water resources for crops. The present study aimed to analyse the spatial distribution of climate variables related to water resources in the olive-growing areas throughout Extremadura, southwestern Spain. To perform this task, three climate variables were used: potential evapotranspiration of the crop, the FAO aridity index and the annual water requirement. Considering data from 58 weather stations located throughout Extremadura and 17 along boundaries with at least 30-year length (within the 1991-2021 period), each variable was computed at each station. After calculating some descriptive statistics, a multivariate geostatistical (regression-kriging) algorithm, incorporating secondary information on elevation and latitude, was used to accurately map each climate variable. Later, temporal trends and their magnitude were analysed using the Mann-Kendall test and the Sen’s estimator, respectively. The highest evapotranspiration and water requirements are located in the southern part of the region, which has large areas dedicated to olive cultivation. In the northern part of the region, there is greater spatial variability in evapotranspiration and, consequently, in water requirements for olive groves due to the more rugged topography. Similarly, the olive-growing areas with the highest aridity are also in the south of Extremadura. In most areas of Extremadura, olive cultivation requires appropriate irrigation for optimal productivity. According to evapotranspiration trends, the water requirements will become greater in the future. However, it is not guaranteed that the water supply will be sufficient in olive-growing areas where aridity is higher and water resources are scarce. The results of this study are very important for evaluating water deficit and water resources in vulnerable olive-growing areas throughout Extremadura.

The present study was conducted in Extremadura, a region in southwestern Spain with a significant area dedicated to olive cultivation. An analysis of the olive growing climatology of its territory was conducted using bioclimatic indices that affect the development of olive cultivation, focusing on water requirements, thermal requirements, and leaf carbohydrate synthesis. The study revealed that very dry conditions during the olive growing season are the main characteristic of the Mediterranean climate in the region. A principal component analysis was performed to analyze the main sources of variability, revealing two main components, determined by annual rainfall, annual water requirement, mean annual temperature, degree days above 14.4 °C accumulated during the olive growing season, and the number of days with optimal temperatures for leaf carbohydrate synthesis. Three homogeneous groups were determined by cluster analysis, one of which had cooler thermal conditions and no water requirements. The study found that an increase in the olive growing season or a shortening of the dormant period could result in a higher water input during the growing season and a lack of accumulation of chilling hours during the dormant period, causing crop maintenance problems in warmer locations. Climate change is expected to have significant impacts on this crop where climatic conditions are already very hot and dry. In the future, it is possible that the current olive-growing areas in Extremadura will move to other areas where the temperature is cooler.

This study analysed the climatic characteristics of olive growing in Extremadura, a region in western Spain with some of the largest areas and production in Europe. A daily database was created from 47 weather stations located throughout Extremadura during the olive growing season from 1990-2021. To characterise and determine the olive growing climatology in Extremadura, the climatic variables and ten bioclimatic-physiological indices that provide information on the be-haviour of the olive tree have been calculated. The correlation between the fourteen variables used was carried out, a reduction was made and the number of minimum factors was determined using principal component analysis (PCA) and, in order to obtain homogeneous groups, cluster analysis was carried out. The result of index reduction revealed that annual rainfall (Rr), annual water re-quirement (AWR), mean annual temperature (Tavg), degree days above 14.4 °C accumulated in the olive growing period (GDD14.4) and the number of days with optimal temperatures for carbohy-drate synthesis in leaves (NDCHS) were sufficient to characterise the agricultural regions of Ex-tremadura, explaining between them 97.24% of the observed variability. The results indicate the presence of two principal components, one pertaining to thermal-physiological factors (PC1) and the other to hydric variables (PC2). Three homogeneous groups were determined by cluster analysis, one of which had cooler thermal conditions and no water requirements. The study found that an increase in the olive growing season or a shortening of the dormant period could result in a higher water input during the growing season and a lack of accumulation of chilling hours during the dormant period, causing crop maintenance problems in warmer locations. Climate change is expected to have significant impacts on this crop where climatic conditions are already very hot and dry. In the future, it is possible that the current olive growing areas in Extremadura will move to other areas where the temperature is cooler.