PHyST-Net: A hybrid seasonal-temporal deep learning framework for climate forecasting and extreme rainfall risk assessment in semi-arid Ghana
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.
- Bruzzone OA, Perri DV, Easdale MH. Vegetation responses to variations in climate: A combined ordinary differential equation and sequential Monte Carlo estimation approach. Ecol Inform. 2023;73:101913. https://doi.org/10.1016/j.ecoinf.2022.101913.
- Singh P. Crop models for assessing impact and adaptation options under climate change. J Agrometeorol. 2023;25(1):18-33. https://doi.org/10.54386/jam.v25i1.1969
- Nicholson SE. The West African Sahel: A review of recent studies on the rainfall regime and its interannual variability. ISRN Meteorol. 2013:1-32. https://doi.org/10.1155/2013/453521
- Antwi-Agyei P, Fraser EDG, Dougill AJ, Stringer LC, Simelton E. Mapping the vulnerability of crop production to drought in Ghana using rainfall, yield and socioeconomic data. Appl Geogr. 2012;32(2):324-334. https://doi.org/10.1016/j.apgeog.2011.06.010
- Giorgi F, Mearns L. Introduction to special section: Regional climate modeling revisited. J Geophys Res Atmos. 1999;104(D6):6335-6352. https://doi.org/10.1029/98JD02072
- Palmer T. Towards the probabilistic earth-system simulator: A vision for the future of climate and weather prediction. Q J R Meteorol Soc. 2012;138(665):841-861. https://doi.org/10.1002/qj.1923
- Maraun D, Wetterhall F, Ireson AM, et al. Precipitation downscaling under climate change: Recent developments to bridge the gap between dynamical models and the end user. Rev Geophys. 2010;48(3). https://doi.org/10.1029/2009rg000314
- Shi X, Chen Z, Wang H, Yeung DT, Wong W, Woo W. Convolutional LSTM network: A machine learning approach for precipitation nowcasting. In: Advances in Neural Information Processing Systems 28. Red Hook, NY, USA: Curran Associates, Inc.;2015:802-810.
- Ojo OS, Ogunjo ST. Machine learning models for prediction of rainfall over Nigeria. Sci Afr. 2022;16:e01246. https://doi.org/10.1016/j.sciaf.2022.e01246
- Adjei CO, Tian W, Onzo BM, Chen S, Kedjanyi EAG, Darteh OF. Rainfall forecasting in sub-Sahara Africa-Ghana using LSTM deep learning approach. IJERTORG. 2021;10(3):464-470. https://doi.org/10.5281/zenodo.18629903
- Jing L, Gulcehre C, Peurifoy J, et al. Gated Orthogonal Recurrent Units: On Learning to Forget. Neural Comput. 2019;31(4):765-783. https://doi.org/10.1162/neco_a_01174
- Sheriff R, Meer MS, Tariq A. Remote sensing-based assessment of vegetation and land surface temperature effects on nitrogen dioxide concentrations in Chennai and Bengaluru using Google Earth Engine. Eng Rep. 2026;8(1). https://doi.org/10.1002/eng2.70436
- Tamimu MG. Sustainable AI-driven predictive modeling in agricultural supply chains: AI, IoT, and blockchain integration for climate adaptation in Ghana. IJEBM. 2026;3(3). https://doi.org/10.33552/ijebm.2026.03.000564
- Seneviratne SI, Nicholls N, Easterling D, et al. Changes in climate extremes and their impacts on the natural physical environment. In: Field CB, Barros V, Stocker TF, Dahe Q, eds. Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation. Cambridge, UK: Cambridge University Press; 2012:109-230. https://doi.org/10.1017/cbo9781139177245.006
- Kasei R, Diekkrüger B, Leemhuis C. Drought frequency in the Volta Basin of West Africa. Sustain Sci. 2009;5(1):89-97. https://doi.org/10.1007/s11625-009-0101-5
- Tamimu MG, Liang D. Sustainable mining development in Ghana: An integrated AHP-TOPSIS-Manhattan distance approach. Resour Policy. 2025;110:105757. https://doi.org/10.1016/j.resourpol.2025.105757
- Tamimu MG, Zhao S, Xu Q, Zhang J. Attention-based deep learning hybrid model for cash crop price forecasting: Evidence from global futures markets with implications for West Africa. Appl Sci. 2026;16(3):1600. https://doi.org/10.3390/app16031600
- Senjaliya J, Vaghasia V, Shah SM. A comprehensive review of machine learning and deep learning approaches for rainfall forecasting: current progress, challenges, and future directions. Theor Appl Climatol. 2026;157(3):177. https://doi.org/10.1007/s00704-026-06051-y
- Vandal T, Kodra E, Ganguly S, Michaelis A, Nemani R, Ganguly AR. Generating high resolution climate change projections through single image super-resolution: An Abridged Version. In: Proceedings of the Twenty-Seventh International Joint Conference on Artificial Intelligence. International Joint Conferences on Artificial Intelligence Organization; 2018:5389-5393. https://doi.org/10.24963/ijcai.2018/759
- Reichstein M, Camps-Valls G, Stevens B, et al. Deep learning and process understanding for data-driven Earth system science. Nature. 2019;566(7743):195-204. https://doi.org/10.1038/s41586-019-0912-1
- Raissi M, Perdikaris P, Karniadakis GE. Physics-informed neural networks: a deep learning framework for solving forward and inverse problems involving nonlinear partial differential equations. J Comput Phys. 2019;378:686-707. https://doi.org/10.1016/j.jcp.2018.10.045
- Yang Y, Perdikaris P. Adversarial uncertainty quantification in physics-informed neural networks. J Comput Phys. 2019;394:136-152. https://doi.org/10.1016/j.jcp.2019.05.027
- Chen Y, Yang Q, Chen Z, Yan C, Zeng S, Dai M. Physics-informed neural networks for building thermal modeling and demand response control. Build Environ. 2023;234:110149. https://doi.org/10.1016/j.buildenv.2023.110149
- Lu L, Meng X, Mao Z, Karniadakis GE. DeepXDE: A deep learning library for solving differential equations. SIAM Rev. 2021;63(1):208-228. https://doi.org/10.1137/19m1274067
- Bonavita M, Geer A, Laloyaux P, Massart S, Chrust M. Data assimilation or machine learning? ECMWF Newsl. 2021;167:17-22. https://www.ecmwf.int/en/newsletter/167/meteorology/data-assimilation-or-machine-learning
- Gadafi TM, Mohammed AMA, Ma J, Muhammad SR, Darko AP, Liang D. BiLSTM-based climate and agricultural supply chain resilience modeling using time series forecasting in Ghana. In: Proceedings of the 2nd International Conference on Image Processing, Machine Learning, and Pattern Recognition. New York, NY, USA: Association for Computing Machinery; 2025:225-230. https://doi.org/10.1145/3759928.3759967
- Yamba EI, Fink AH, Badu K, Asare EO, Tompkins AM, Amekudzi LK. Climate drivers of malaria transmission seasonality and their relative importance in sub-Saharan Africa. GeoHealth. 2023;7(2):e2022GH000698. https://doi.org/10.1029/2022gh000698
- Nwazelibe VE, Agbasi JC, Arunachalam KP, Usman AG, Abba SI, Egbueri JC. Monthly rainfall forecasting for southern Nigeria using 2D deep learning and implications for climate adaptation and sustainability: A CNN-LSTM+Attention approach. Phys Chem Earth Parts A/B/C. 2026;144:104577. https://doi.org/10.1016/j.pce.2026.104577
- Karpatne A, Atluri G, Faghmous JH, et al. Theory-guided data science: A new paradigm for scientific discovery from data. IEEE Trans Knowl Data Eng. 2017;29(10):2318-2331. https://doi.org/10.1109/tkde.2017.2720168
- Pradhan R, Aygun RS, Maskey M, Ramachandran R, Cecil DJ. Tropical cyclone intensity estimation using a deep convolutional neural network. IEEE Trans Image Process. 2018;27(2):692-702. https://doi.org/10.1109/tip.2017.2766358
- Aghenda M, Labbaci A, Bouchaou L, et al. Flood prediction using machine learning and deep learning models: a systematic review. Med Geosc Rev. 2025;7(4):1149-1167. https://doi.org/10.1007/s42990-025-00201-6
- Stengel K, Glaws A, Hettinger D, King RN. Adversarial super-resolution of climatological wind and solar data. Proc Natl Acad Sci USA. 2020;117(29):16805-16815. https://doi.org/10.1073/pnas.1918964117
- Mwendera EJ. Rural water supply and sanitation (RWSS) coverage in Swaziland: Toward achieving millennium development goals. Phys Chem Earth Parts A/B/C. 2006;31(15-16):681-689. https://doi.org/10.1016/j.pce.2006.08.040
- Asare-Kyei D, Forkuor G, Venus V. Modeling flood hazard zones at the sub-district level with the rational model integrated with GIS and remote sensing approaches. Water. 2015;7(7):3531-3564. https://doi.org/10.3390/w7073531
- Owusu K, Waylen PR. The changing rainy season climatology of mid-Ghana. Theor Appl Climatol. 2012;112(3-4):419-430. https://doi.org/10.1007/s00704-012-0736-5
- Afriyie R, Bessah E, Attoh EMNAN, et al. Climate information services and farm-level decision-making in the Pra River Basin of Ghana. Discov Environ. 2026;4:335. https://doi.org/10.1007/s44274-026-00655-x
- Dunee D, Dagadu PP, Ayimadu ET, et al. Impact of climate change on water resources and its implications on biodiversity, flood disasters, and food security in Ghana: a review. GeoJournal. 2025;90(3). https://doi.org/10.1007/s10708-025-11348-y
- Unami K, Abagale FK, Yangyuoru M, Badiul Alam AHM, Kranjac-Berisavljevic G. A stochastic differential equation model for assessing drought and flood risks. Stoch Environ Res Risk Assess. 2009;24(5):725-733. https://doi.org/10.1007/s00477-009-0359-2
