Trends in minimum winter temperatures and date of the last spring frost in the main fruit-growing areas of Spain

The agricultural sector, and particularly the production of temperate fruit trees, is being severely affected due to climate change. Undoubtedly, warmer winters and earlier springs reduce the availability of cold hours as well as produce changes in frost regimes and their severity. The Mediterranean region and the Iberian Peninsula (PI) are among the areas where the greatest impact of climate is expected. Daily data from six meteorological stations in the main fruit areas of the IP have been used to assess trends (1975-2020). The variables analyzed are absolute minimum annual average temperature and the last day of spring frosts. The trends of the variables were investigated using the Mann-Kendall test and Sen’s slope estimator. The results show an increase in the mean absolute minimum temperature (values between 0.06 and 0.10°C year^‑1), with very high significant trends in Murcia and Seville. Average frost dates vary greatly due to the orographic characteristics and the interannual variability of our climate, but the generalized and significant trend is of an advance of the frosts of early spring (between 0.48 and 1.30 days year^‑1) and, as a consequence, a higher risk of damage during flowering. These magnitudes found were more important than those found in other regions of the world. These effects of climate change will need to be mitigated using cultivars with lower cold requirements and with flowering dates in accordance with the new frost regime to guarantee sustainable agriculture.