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Fire weather severity in Southern Africa is increasing faster and more extensively in the late than in the early dry season

Sílvia Catarino , João Silva, Alana Neves, Duarte Oom, José Pereira

Abstract

Background: In the African savannas, the most intense fires typically occur during the late dry season, when fuel availability is high, and atmospheric relative humidity is low. The Fire Weather Index (FWI) system has been used to measure the effort required for fire suppression and explore the impact of climate on fires. Aims: This study assesses trends in FWI components from 1979 to 2022 and their influence on burned area (BA). Methods: We employed the Theil–Sen slope estimator and the contextual Mann–Kendall test to evaluate the presence of significant trends in FWI components during the early dry season (EDS) and the late dry season (LDS). Additionally, we analyzed trends in BA and assessed how they depend on fire weather. Key results: Our findings reveal distinct patterns in fire weather trends between the EDS and LDS, with the LDS showing more widespread areas of increasing trends. However, only 28% of the regression analyses showed significant relationships with BA, suggesting that FWI components have a moderate influence on BA interannual variance. Conclusions: Fire weather severity is increasing faster and more extensively in the LDS than in the EDS. Additional factors beyond weather also play a significant role in shaping BA trends. Proactively managing anthropogenic fires during the moister EDS can help mitigate fire intensity, reduce emissions, and support biodiversity conservation efforts.

WF24002  Accepted 14 February 2025

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