TIAN et al. (2026) Intensifying droughts, heatwaves, and compound drought–heatwave events and their spatiotemporal patterns in Africa (1979–2024)

Identification

• Journal: Weather and Climate Extremes
• Year: 2026
• Date: 2026-03-01
• Authors: Peng TIAN, Shenghao Wu, Yanyun Yan, Hang Wang, Jialin Li, Yongchao Liu, Haitao Zhang, Chao Ying
• DOI: 10.1016/j.wace.2026.100879

Research Groups

• College of Life and Environmental Science, Wenzhou University, Wenzhou, China
• Zhejiang Provincial Key Laboratory of Water Ecological Environment Treatment and Resource Protection, Wenzhou University, Wenzhou, China
• School of Biology & Environmental Science, Queensland University of Technology, Brisbane, QLD, Australia
• School of Geography and Remote Sensing, Ningbo University, Ningbo, Zhejiang, China
• School of National Safety and Emergency Management, Beijing Normal University, Beijing, China

Short Summary

This study systematically evaluates the spatiotemporal patterns of heatwaves, droughts, and compound drought–heatwave (CDHW) events across Africa from 1979 to 2024, revealing significant intensification of all three, with CDHWs accelerating since the 2000s, particularly in Eastern and Southern Africa.

Objective

• To reveal the variability and trends of droughts and heatwaves at continental, climatic, regional, and national scales across Africa.
• To quantify the frequency, duration, and intensity of CDHWs and assess their long-term dynamics.
• To disentangle the relative contributions of drought and heatwave conditions to CDHW formation.

Study Configuration

• Spatial Scale: Africa (continental, climate zones (Koppen-Geiger), IPCC reference regions, and national levels).
• Temporal Scale: 1979–2024 (46 years).

Methodology and Data

• Models used:
  • Event-based Compound Drought–Heatwave (CDHW) framework.
  • Grouped modeling framework (linear and logistic regression) for contribution analysis.
  • Mann–Kendall (MK) test and Sen's slope estimator for trend analysis.
• Data sources:
  • Multi-Source Weather (MSWX) dataset (0.1° spatial resolution, 3-hourly temporal resolution) for maximum land surface temperature (Tmax).
  • ERA5–Drought dataset (0.25° spatial resolution, monthly temporal resolution) for Standardized Precipitation Evapotranspiration Index (SPEI-3).
  • World Bank Official Boundaries for geographical masks.

Main Results

• All heatwave metrics (duration, total days, cumulative intensity, mean intensity, maximum temperature, frequency) across Africa showed significant upward trends from 1979 to 2024, with acceleration after 2010.
• Heatwave seasons significantly lengthened, with the mean onset date advancing from April 8 to February 17 and the end date delaying from June 30 to September 12. Arid and semi-arid regions showed the earliest onsets and greatest seasonal extensions.
• Drought conditions intensified markedly across Africa, with annual mean drought hazard duration increasing from 0.72 months to 3.97 months, frequency from 0.79 events per year to 4.95 events per year, and cumulative intensity from 0.42 to 5.40 (dimensionless units).
• Compound Drought–Heatwave (CDHW) events intensified substantially since the early 2000s, with annual CDHW_Days frequently exceeding 60–80 days and cumulative intensity tripling compared to the 1980s.
• CDHW activity peaks in boreal spring (March–April–May) and summer (June–July–August), with Eastern and Southern Africa (especially Southeastern Africa and Eastern Southern Africa) experiencing the longest event durations and highest cumulative intensities.
• Contribution analysis revealed that drought-related predictors explain a larger fraction of variability in CDHW occurrence (R² = 0.804), frequency (R² = 0.316), and cumulative intensity (R² = 0.184), while heatwave-related predictors primarily influence event duration (R² = 0.248).

Contributions

• Provides the first systematic, pan-continental investigation of compound drought–heatwave (CDHW) events across Africa at multiple scales (continental, climatic, regional, and national) using long-term (1979–2024) datasets.
• Quantifies the spatiotemporal characteristics and long-term dynamics of heatwaves, droughts, and CDHWs, addressing a significant knowledge gap in a climate-vulnerable region.
• Disentangles the relative contributions of heatwave and drought conditions to CDHW formation, revealing regionally differentiated drivers (drought dominates occurrence/intensity, heatwaves dominate duration).
• Highlights Africa-specific features of CDHW variability, such as extended event duration and strong seasonal cycles, which extend the understanding of compound extremes beyond global trends.

Funding

• National Natural Science Foundation of China (42276234 and 42206236).

Citation

@article{TIAN2026Intensifying,
  author = {TIAN, Peng and Wu, Shenghao and Yan, Yanyun and Wang, Hang and Li, Jialin and Liu, Yongchao and Zhang, Haitao and Ying, Chao},
  title = {Intensifying droughts, heatwaves, and compound drought–heatwave events and their spatiotemporal patterns in Africa (1979–2024)},
  journal = {Weather and Climate Extremes},
  year = {2026},
  doi = {10.1016/j.wace.2026.100879},
  url = {https://doi.org/10.1016/j.wace.2026.100879}
}