In January 2024, high pressure-area from China mainly extended its ridge to cover northeastern part and the South China Sea and the westerly wind in the upper level prevailed over the northern part sometimes resulting in an overall mild winter in Thailand with cool weather in the northern and northeastern parts and cold weather in upper northern in some periods whereas cool weather in several areas in the other parts. The mean temperature was 1-2 o C above normal nationwide especially in Chiang Rai, Chiang Mai, Nan and Phayao provinces where the temperature excess 2.0 o C. The average temperature over Thailand in this month was 1.4 o C higher than normal. For rainfall, there was no rain reported in upper Thailand in the beginning and the middle of the month while unusual rain was observed at the end of the month due to the passage of the westerly trough over upper northern, upper central and upper northeastern parts accompanied with the prevailing of the southerly and southeasterly winds over upper Gulf of Thailand, lower central and eastern parts. In southern part, the northeast monsoon prevailed over the Gulf of Thailand and southern part throughout the entire month caused intermittent rainfall mainly along the east coast. The monthly rainfall was lower than normal in all parts i.e. northern part 0.2 millimeter (2%), northeastern part 3.1 millimeter (46%), central 6.5 millimeter (61%), eastern part 12.2 millimeter (53%), southern part (east coast) 30.6 millimeter (29%) and southern part (west coast) 36.6 millimeter (73%). The averaged total rainfall over Thailand in this month was 38% lower than normal. More details were as follow.