The analysis of the Landsat satellite images revealed a significant increase in the area of thermokarst lakes in Central Yakutia over the period 2000–2019. The lake area increased twice in the basins of the Suola and Taatta River basins and by 25 % in the Tanda River basin. It has been established that, despite the presence of a general linear trend, the increase in the area of lakes occurs abruptly. Qualitative relationship between the changes in the state of the upper layer of permafrost and the dramatical increase in the area of thermokarst lakes has been revealed. The main factor leading to disruption of a stable state of thermokarst forms are short-term (1–3 years) periods of sudden changes in temperature of seasonally thawed layer from below-average to anomalously high values. These periods can be caused by a rare combination of hydrometeorological conditions, such as anomalously high values of snow water equivalent, increased annual precipitation, and an increased water content of soils of the seasonally thawed layer.