https://doi.org/10.30598/barekengvol16iss1pp137-146 March 2022 Volume 16 Issue 1 Page 137–146 P-ISSN: 1978-7227 E-ISSN: 2615-3017 BAREKENG: Jurnal Ilmu Matematika dan Terapan 137 https://ojs3.unpatti.ac.id/index.php/barekeng/ barekeng.math@yahoo.com FORECASTING RAINFALL IN PANGKALPINANG CITY USING SEASONAL AUTOREGRESSIVE INTEGRATED MOVING AVERAGE WITH EXOGENOUS (SARIMAX) Ririn Amelia 1* , Elyas Kustiawan 2 , Ineu Sulistiana 3 , Desy Yuliana Dalimunthe 4 1,2,3,4 Mathematics Department, Faculty of Technic, Universitas Bangka Belitung Kampus Terpadu Universitas Bangka Belitung, Balunijuk, Bangka Regency, 33172, Indonesia Corresponding author e-mail: ¹* ririn-amelia@ubb.ac.id Abstract. Changes in extreme rainfall can cause disasters or losses for the wider community, so information about future rainfall is also needed. Rainfall is included in the category of time series data. One of the time series methods that can be used is Autoregressive Integrated Moving Average (ARIMA) or Seasonal ARIMA (SARIMA). However, this model only involves one variable without involving its dependence on other variables. One of the factors that can affect rainfall is wind speed which can affect the formation of convective clouds. In this study, the ARIMA model was expanded by adding eXogen variables and seasonal elements, namely the SARIMAX model (Seasonal ARIMA with eXogenous input). Based on the analysis that has been carried out, the prediction of rainfall in Pangkalpinang City, Bangka Belitung Islands Province can be modeled with the SARIMAX model (0,1,3)(0,1,1){12} for monthly rainfall and SARIMAX (0,1,2 )(0,1,3){12} for maximum daily rainfall. When compared with the actual data and previous studies using ARIMAX, the SARIMAX model is still better in the forecasting process when compared to the ARIMAX model. If viewed based on the AIC value of the SARIMA model, the SARIMAX model is also more suitable to be used to predict rainfall in Pangkalpinang City. Keywords: forecasting, rainfall, sarima, sarimax Article info: Submitted: 24 th November 2021 Accepted: 7 th February 2022 How to cite this article: R. Amelia, E. Kustiawan, I. Sulistiana and D. Y. Dalimunthe, “FORECASTING RAINFALL IN PANGKALPINANG CITY USING SEASONAL AUTOREGRESSIVE INTEGRATED MOVING AVERAGE WITH EXOGENOUS (SARIMAX)”, BAREKENG: J. Il. Mat. & Ter., vol. 16, iss. 1, pp. 137-146, Mar 2022. This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License. Copyright © 2022 Ririn Amelia, Elyas Kustiawan, Ineu Sulistiana, Desy Yuliana Dalimunthe