National Climate Status of Madagascar: Rainfall and Temperature Trends (1950 - 2025)

Abstract

This study presents an analysis of climate trends observed in Madagascar over the period from 1950 to 2025, focusing on nine standardized climate indices for precipitation and temperature (TX90p, TN90p, SU25, TR20, RD, R10mm, R20mm). The methodological approach is based on the recommendations of McKee et al. (1993) for calculating standardized anomalies and classifying excesses/deficits into seven classes (±0.5; ±1; ±2). The daily data are sourced from the fixed-site network of Madagascar\'s Directorate General of Meteorology (DGM). The results indicate a significant warming trend across the entire territory, with an increase in positive mean temperature anomalies frequently exceeding +0.255°C per decade compared to the 1991 - 2020 normal. From a national perspective, the TX90p (hot days) heat index does not show a significant detected trend, while the TN90p (hot nights) index shows a decreasing trend of -0.062 per decade. With regard to precipitation, the results are more mixed: although the national average shows a slight but significant downward trend (-0.067 per decade), there has been an increase in interannual variability, characterized by alternating years of moderate surpluses and moderate deficits. This study thus provides an updated basis for the development of climate change adaptation policies in Madagascar.

Introduction

The text presents a climate study of Madagascar, a country highly vulnerable to climate change despite contributing very little to global greenhouse gas emissions. The island frequently experiences extreme events such as droughts, cyclones, and floods, making climate analysis essential for food security and development planning.

Previous studies have shown clear climate changes, including rising temperatures, more frequent warm nights, and shifting rainfall patterns, but they often use inconsistent datasets and methodologies. This study addresses these gaps by creating a unified analysis of climate trends in Madagascar from 1950 to 2025 using standardized data from 17 meteorological stations.

The methodology uses quality-controlled weather data (precipitation and temperature), nine climate indices (such as hot days, rainy days, and heavy rainfall events), and standardized anomaly calculations (Z-scores) based on a 1991–2020 reference period. Climate variations are then classified into seven categories ranging from severe deficit/cold to strong surplus/heat, following WMO guidelines.

Conclusion

This study analyzed precipitation and temperature trends in Madagascar for the period 1950 - 2025, using a standardized methodology in accordance with WMO recommendations (McKee et al., 1993; Klein Tank & Können, 2003) [7], [9]. The main findings are as follows: - Significant warming: the annual average temperature is rising by +0.255°C per decade (p = 0), a rate higher than the global average (World Bank, 2024) [3]. The years 2019 and 2024 were the warmest on record. - Asymmetry in warming: Tropical nights (TR20) are increasing more rapidly (+0.369 per decade) than summer days (SU25, +0.355 per decade). - Intensification of extreme precipitation: Annual precipitation shows a slight but significant decrease (0.067 per decade), while the number of days with very heavy rain (R20mm) is decreasing very slightly (-0.061 per decade). These findings provide a scientific basis for the development of climate change adaptation policies in Madagascar (National Adaptation Plan, Nationally Determined Contribution). Future work should include: - A spatial analysis at the regional level (South, East, Central, West, North) to identify the most vulnerable areas (IOM, 2024) [13]. - The integration of satellite data to improve spatial coverage in undersampled regions (UNICEF/JRC, 2024) [12]. - Projections for 2050 and 2100 based on CMIP6 models [6]. - An attribution analysis to distinguish anthropogenic forcings from natural variability [6].

References

[1] Banque Mondiale (World Bank), (2024). Rapport national sur le climat et le développement de Madagascar (CCDR). [2] Amnesty International, (2025). \"That Suffering Haunts Me Even Here\": The Struggle for Human Rights of the Antandroy People Displaced by Climate Change from Southern Madagascar. [3] World Bank Group, (2024). Madagascar Country Climate and Development Report: Disaster Risk Management and Urban Resilience - Background Note. [4] Mark Tadross, Luc Randriamarolaza, Zo Rabefitia, Zheng Ki Yip, (2008). Climate change in Madagascar; recent past and future. [5] Randriamarolaza L.Y.A. (2021). Indices for daily temperature and precipitation in Madagascar, based on quality controlled and homogenized data, 1950 - 2018. https://doi.org/10.1002/joc.7243 [6] Randriamarolaza L.Y.A. (2023). Extreme temperatures detection and attribution related to external forcing in Madagascar. https://doi.org/10.1002/joc.8065 [7] Direction Générale de la Météorologie de Madagascar, (2023). Les tendances climatiques observées et les futurs changements climatiques à Madagascar 2023 (3ème édition). [8] Judy M. Olson & Cynthia A. Brewer. (1997). An Evaluation of Color Selections to Accommodate Map Users with Color-Vision Impairments. Annals of the Association of American Geographers, 87(1), 103–134. https://doi.org/10.1111/0004-5608.00043 [9] McKee T.B., Doesken N.J., Kleist J. (1993). The relationship of drought frequency and duration to time scales. Department of Atmospheric Science Colorado State University Fort Collins, CO 80523 [10] Spinoni J., Barbosa P., De Jager A., et al. (2019). A new global database of meteorological drought events from 1951 to 2016. https://doi.org/10.1016/j.ejrh.2019.100593 [11] World Meteorological Organization (WMO), (2017). Guidelines on Generating a Defined Set of National Climate Monitoring Products. WMO-No. 1204. [12] UNICEF / European Commission Joint Research Centre, (2024). Bulletins d\'alerte sécheresse du Grand Sud de Madagascar. [13] IOM (International Organization for Migration), (2024). Solutions and Mobility Index - Great South Region / Menabe Region.

Copyright

Copyright © 2026 Sitraka Ravelomantsoa, Bienvenue Raheliarilalao. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.