NEBIYU MOHAMMED WOYESO2026-02-022024-05https://etd.hu.edu.et/handle/123456789/473Global warming has garnered significant attention in recent years due to its profound implications for the environment, economy, and society. This study aims to model and forecast the monthly average temperature globally and in East Africa using time series analysis. Secondary data from the Berkeley method, spanning from 1850 to the present, were utilized. The average temperatures recorded were 14.103°C globally, 23.025°C in Ethiopia, 23.979°C in Kenya, and 23.019°C in Uganda. After applying the first seasonal differencing to achieve stationarity, statistical models such as SARIMA were employed. Based on Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC), SARIMA(4,0,0)(0,1,1,12) for global temperatures, SARIMA(2,0,2)(3,1,1,12) for Ethiopia, SARIMA(2,0,3)(0,1,1) for Kenya, and SARIMA(1,0,4)(0,1,1,12) for Uganda were identified as the best-fit models. Forecasts for the next two decades indicate an increasing temperature trend across all regions. Model performance was evaluated using metrics such as Mean Absolute Error (MAE), Root Mean Square Error (RMSE), and Mean Absolute Percentage Error (MAPE), all of which indicated good forecasting accuracy. To capture temperature volatility, ARCH/GARCH models, including ARCH, GARCH, and EGARCH, were applied. The EGARCH models were found to be most effective, with EGARCH(4,1) for global temperatures, EGARCH(3,1) for Ethiopia, EGARCH(3,2) for Kenya, and EGARCH(4,1) for Uganda showing superior performance based on lower AIC and BIC values and higher log-likelihood values. The findings have significant implications for climate adaptation planning, particularly in regions like East Africa that are highly susceptible to climate change impacts. By providing reliable forecasting tools, this study supports efforts in agricultural planning, water resource management, energy demand forecasting, public health, and environmental impact assessment.en-USTemperatureTime Series AnalysisSARIMAEast AfricaThesis