AccScience Publishing / NSCE / Online First / DOI: 10.36922/NSCE026250025
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RESEARCH ARTICLE

PHyST-Net: A hybrid seasonal-temporal deep learning framework for climate forecasting and extreme rainfall risk assessment in semi-arid Ghana

Toufic Seini1 ,  Daniel Makinde Oluwole2 ,  Ibrahim Yakubu Seini1 ,  Mohammed Gadafi Tamimu3,4*
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1 Department of Mathematics, Faculty of Physical Sciences, University for Development Studies, Tamale, Northern Region , Ghana
2 Faculty of Military Science, Stellenbosch University, Stellenbosch, Western Cape , South Africa
3 College of International Communication and Cooperation, Sichuan University of Culture and Arts, Mianyang, Sichuan , China
4 School of Economics and Management, Center for West African Studies, University of Electronic Science and Technology of China, Chengdu, Sichuan , China
Received: 17 June 2026 | Revised: 20 August 2026 | Accepted: 1 September 2026 | Published online: 15 September 2026
© 2026 by the Author(s). This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution -Noncommercial 4.0 International License (CC-by the license) ( https://creativecommons.org/licenses/by-nc/4.0/ )
Abstract

Accurate forecasting of temperature and rainfall is critical for climate adaptation, agricultural planning, water-resource management, and disaster risk reduction, particularly in semi-arid regions where climate variability poses significant socio-economic challenges. Climate prediction in data-limited regions remains difficult due to nonlinear temporal interactions, seasonal variability, and the rarity of extreme rainfall events. This study proposes the physics-aware spatio-temporal network (PHyST-Net), a hybrid seasonal-temporal deep learning framework that integrates 1D convolutional neural networks (CNNs) and bidirectional long short-term memory (LSTM) networks for multivariate climate forecasting and extreme rainfall risk assessment in semi-arid Ghana. Unlike conventional statistical models, PHyST-Net combines local temporal feature extraction through CNN layers with long-range sequential dependency modeling through bidirectional LSTM layers. It incorporates climate-informed temporal variables, including seasonal month and long-term year indicators, and employs various diagnostic tools, uncertainty estimation, and gradient-based saliency analysis to improve model interpretation. The framework is evaluated using monthly temperature and rainfall observations obtained from the Ghana Meteorological Agency. A chronological 70%–15%–15% training–validation–testing strategy was adopted, using a 36-month historical window for prediction. Experimental results show that PHyST-Net outperformed the persistence, autoregressive integrated moving average, and standalone LSTM models. For temperature forecasting, PHyST-Net achieved a root mean square error (RMSE) of 3.64 °C and mean absolute error (MAE) of 3.08 °C, while rainfall forecasting achieved an RMSE of 19.7 mm and MAE of 14.9 mm. Extreme rainfall detection was formulated as a rare-event classification problem using a statistical rainfall threshold. The classifier provided probabilistic estimates of extreme rainfall occurrence, while calibration, precision–recall analysis, and probability-based interpretation were used because extreme rainfall events are highly imbalanced. Overall, PHyST-Net offers a robust and interpretable framework for climate forecasting and extreme-event risk assessment in data-limited regions.

Keywords
Climate forecasting
Convolutional neural network–bidirectional long short-term memory
Extreme rainfall detection
Time-series forecasting
Deep learning
Climate risk assessment
Ghana
Funding
None.
Conflict of interest
The authors declare they have no competing interests.
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