Authors : Ibrahim Tunji Awolere; Sabastine Dekaa Francis; Oduyomi Michael Badejo; Modupe Stella Omotayo-Tomo

Volume/Issue : Volume 11 - 2026, Issue 5 - May

Google Scholar : https://tinyurl.com/ve5423sn

DOI : https://doi.org/10.38124/ijisrt/26may1810

Note : A published paper may take 4-5 working days from the publication date to appear in PlumX Metrics, Semantic Scholar, and ResearchGate.

Abstract : Climate change and variability have become global concerns due to their wide-ranging effects on the environment, human health, agriculture, and water resources. Among the key indicators of climate change are changes in rainfall patterns. These changes are not only global but are also evident at the regional and local levels. Ondo State, located in the southwestern part of Nigeria, has a stretch of coastal land along the Atlantic Ocean. This region is particularly vulnerable to the effects of climate change due to its geographical location. Changes in rainfall and patterns in this area can have serious implications for agriculture, fishing, water availability, and general livelihood. Communities in coastal Ondo State rely heavily on rainfall for crop cultivation and productive farming seasons. Unpredictable weather conditions could therefore threaten food security and economic stability in the region. Previous studies, have observed variations in rainfall and temperature across Ondo State, highlighting signs of climate variability. However, there is still a need for more localized studies focusing specifically on the coastal areas, which may experience different climate dynamics compared to the inland parts of the state. The study area, Ilaje located in Ondo state, has a stretch of coastal land along the Atlantic Ocean. Changes in the rainfall pattern in the area can have serious implications on agriculture, fishing, and general livelihood. These changes affect crop yields, fishing patterns, access to clean water, and even the overall health of the environment. By identifying and analyzing long-term trends in these climate variables, this research can help provide useful information for farmers, fishermen, and other residents of the area who depend on predictable weather for their daily activities. The study aims to investigate the long-term changes in rainfall patterns over the coastal areas of Ondo State, to focus more specifically on the coastal region, which may experience different or more intense climate dynamics due to its location along the Atlantic coastline. The objectives of the study are to; derived equations for calculating the monthly rainfall, annual rainfall, deviations and standardized anomalies for the study area, examine the pentad and decadal changes in rainfall pattern over Ilaje, identify the long-term changes in the monthly and annual rainfall pattern, determine the deviations in the Monthly and Annual rainfall over Ilaje, determine the anomalies and standardized anomalies of rainfall over Ilaje for the study period. In this research, thirty years (1991-2020) daily historical rainfall data of Ilaje were utilized, governing equations derived, R and Python programs were used to analyzed the data and obtained the means, deviations, standard deviations, and standardized anomalies. The results were presented using charts and graphs in order to visually represent rainfall pattern and trends. Results showed that highest positive deviation from normal was 546.5mm (1994). Highest negative deviation of -39.2mm, was observed in 2015. On monthly basis, highest normal rainfall of 256.7mm (September),231.6mm (October), and 205.9mm (June), were identified. Lowest monthly normal rainfalls were observed in January (10.7mm), December (10.9mm) and February (30.0mm). Highest monthly rainfall of 508.3mm occurred in July, 1994. Change analysis showed 1991-1995 pentad had the highest mean rainfall of 1737.7mm, and 2016-2020 pentad had the lowest mean rainfall of 1400.9mm. It was generally observed that from 1991-1995, rainfall continued to decrease, but increased again in 2010, thereafter, it continued its downward trend. The decadal changes showed a downward trend as mean rainfall of 1645.7mm in the 1991-2000 decadal decreased to 1534.3mm (2001-2010) and further decreased to 1430.9mm in the 2011-2020 decade. By using statistical techniques to identify trends and variations, the study provides a better understanding of the local climate situation. The findings can help government agencies, policymakers, and communities make informed decisions on adaptation strategies and sustainable resource planning in the face of climate change.

Keywords : Rainfall Anomalies, Deviation, Normal, Pentad, Decadal, Rainfall Pattern.

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