AbstractClimatological data from a scientific field study conducted in the Sakaerat Forest, Thailand, from November, 1967 to September, 1970 are summarized and presented. The forest area is comprised of dry evergreen and dry dipterocarp forest with cleared areas in various stages of regeneration. The forest canopy ranges from 20–35 m in height with a lower story ranging from 5–17 m in height.Diurnal and/or seasonal variations of temperature, humidity, precipitation, evaporation, moisture advection and hours of sunshine are analyzed to identify the climatological make-up of the forest area in the context of the moist southwest and dry northeast monsoonal cycles dominating Southeast Asia. Data from eleven other locations in Southeast Asia are pooled with the data from Sakaerat Forest to obtain a coherent picture of the complex monsoon system in this area of the world.(Publication Nr. 105 of the Graduate Program in Meteorology).