Analyzing the intraday dataset on weather and market information with the use of the extended GJR-GARCH framework, this study explores in depth the weather effects on the asset returns and volatilities of the Korean stock and derivatives markets. Our intraday analyses contribute to the existing literature by going beyond the attempt of prior studies to capture the weather effects using the average daily observations alone. The empirical results document a modest presence of the weather effect on the returns and volatilities, though the significance of its impact is found to vary across different market conditions and indices. We also find that the return and volatility respond asymmetrically to extremely good and bad weather conditions. The intraday analyses show that the weather effect on the returns and volatilities is more statistically significant at the beginning of the working day or the lunch break, indicating the intraday weather effects on the financial market.