Occurrence, frequency, and trends of heatwaves and cold spells in Maputo under climate change conditions (1984-2023)

This study analyzed changes in temperature extremes in Maputo, Mozambique, focusing on heatwave and cold-spell frequency and duration in the context of climate change and their direct impacts on agrometeorology and plant-soil-atmosphere relationships. Using daily maximum and minimum temperature data from the ERA5-LAND reanalysis database for the period 1984–2023, rigorously validated with an imputation RMSE of 0.05 °C and emphasizing the climatological normal for 1991–2020 computed through a mathematically robust 5-day moving window, the study applied indices recommended by the World Meteorological Organization (WMO) and the Expert Team on Climate Change Detection and Indices (ETCCDI). These indices include daily percentiles for hot days (TX90p) and cold nights (TN10p), as well as duration indices for heatwaves (WSDI) and cold spells (CSDI), assessed using Sen's slope estimator and the non-parametric Mann-Kendall test. Results indicate that over the last three decades, a non-significant increase occurred in the frequency of hot days (p = 0.144), accompanied by a decrease in the frequency of cold nights (p = 0.161), as well as a non-significant decline in the number of cold spells (p = 0.243). Although the trend in heatwaves was not statistically significant throughout the study period (p = 0.418), an apparent episodic intensification has occurred since 2010, particularly during years associated with El Niño events. These findings are essential for developing public policies focused on adaptation of climate change, urban planning, and resilience strategies, particularly in agricultural, health, and infrastructure sectors in Maputo. In addition, they reinforce the importance of continuous monitoring of temperature extremes to mitigate adverse impacts of climate change, not only in Maputo but also in other coastal cities across Southern Africa.