Northeast Thailand is a crucial rice-producing region, hosting 60% of the nation’s rice paddies, yet over 90% of its fields are rain-fed, rendering them susceptible to variations in precipitation. Therefore, there is an acute need to study the impact of changes in precipitation on rice cultivation in the region. While numerous studies have examined how climate change affects rice production, most have focused on yield variations, neglecting the fluctuation in planted areas. Additionally, previous studies have often relied on fixed planting dates without considering annual or regional variations. This leads to an overestimation of rice production, especially in rain-fed fields where the extent of the planted area is strongly influenced by the volume of precipitation. In this study, we developed a model that estimates planted areas in Northeast Thailand by a water balance approach, integrating meteorological, elevation, and surface water level data. The model not only predicts the planted area but also the planting date, incorporating daily precipitation data to anticipate the spatiotemporal expansion of planted areas. The model calculates the surface water level, designating the day it exceeds 50 mm as the planting date. Model parameters were calibrated using observed data from 2004 and 2005. We then assessed the impact of precipitation changes on planted area extents by inputting climate data from 1981- 2017. In analyzing the temporal changes in planted area and planting date, the model revealed significant differences between past and recent practices. Specifically, when comparing decadal shifts in planted areas from 1981-1990 and 2008-2017, the model revealed that during the former period, many areas were planted in June, while during the latter period, planting dates had become more variable. Furthermore, a comparative analysis of four periods of 1981-1990, 1991-2000, 2001-2010, and 2008-2017 indicated a progressive delay in the planting date over time, due to the increasing uncertainty of precipitation during the early part of the rainy season.