Urban heat island density and occurrence are closely related to land use/land cover and land surface temperature variation. The effect of UHI can be described quantitatively with the urban thermal area variance index. This study aims to evaluate the UHI effect of the city of Samsun with the UTFVI index. LST data from 2000 ETM + and 2020 OLI/TIRS Landsat images were used to analyze UHI. The results showed that the UHI effect increased in Samsun's coastline band in 20 years. As a result of the field analysis made from the UTFVI maps created, in 20 years, 84% decrease in the none slice, 104% increase in the weak slice, 10% decrease in the middle slice, 15% decrease in the strong slice, 8% increase in the stronger slice, and 179% increase in the strongest slice are observed. The slice with the most intense increase is in the strongest slice and reveals the UHI effect.