Next tables present the detail description of the datasets developed in REACHOUT to characterize heat phenomena at city level by providing an assessment of the land surface temperature (heatmaps) of three European cities: Milan, Logroño and Athens. TECNALIA is the responsible partner for these datasets. There is a wide range of methods that can be used to characterise the thermal behaviour of a city, each of them with its advantages and disadvantages. One of these methods uses the land surface temperature that is obtained from remote sensing observations. Although thermal indices are considered more suitable when characterising thermal comfort, still the LST can provide a useful information about the behaviour of a citiy’s surfaces and materials. This has implications for several applications such as urban energy efficiency or urban environmental health. The input data used by the current version of the dataset came from Landsat 8. All the images acquired since 2013 by this satellite for Milan, Logroño and Athens were downloaded and processed to characterise not only the current (2019-2023) thermal behaviour of the city, but also its evolution considering the last seven 5-year windows. - 2013-2017- 2014-2018- 2015-2019- 2016-2020- 2017-2021- 2018-2022- 2019-2023 The input data used in this dataset come from Landsat 8 downloaded from Earth Explorer (usgs.gov). The format of this dataset is organized in two ZIP format files: - LANDSAT_8_L2SP_000000-milan_LST_peak.zip - LANDSAT_8_L2SP_000000-logrono_LST_peak.zip - LANDSAT_8_L2SP_000000-athens_LST_peak.zip Each of these zip files contain seven TIF images that represent the peak LST map according to the images of the above mentioned seven periods. The peak LST is obtained after getting the Annual Cycle Parameters of each of the periods and selecting a 30-day window centred on the day that the city reaches the maximum LST. The values of the images are in degree Celsius and nodata value is -9999.