Heatwaves and Summer Urban Heat Islands: A Daily Cycle Approach to Unveil the Urban Thermal Signal Changes in Lisbon, Portugal

Lisbon is a European Mediterranean city, greatly exposed to heatwaves (HW), according recent trends and climate change prospects. Considering the Atlantic influence, air temperature observations from Lisbon’s mesoscale network are used investigate interactions between background weather urban thermal signal (UTS) in summer. Days classified prevailing regional wind direction, hourly UTS compared HW non-HW conditions. Northern-wind days predominate, revealing greater maximum temperatures (up 40 °C) amplitudes (approximately 10 °C), account for 37 out of 49 days; southern-wind have milder temperatures, no HWs occur. Results show that direction groups significantly different. While minor variations, northern-wind consistent daily cycle: diurnal cooling island (UCI) (often lower than –1.0 late afternoon peak heat (UHI) (occasionally surpassing 4.0 stable nocturnal UHI (1.5 °C median intensity). UHI/UCI intensities not different conditions, although synoptic influence noted. indicate that, Lisbon, intensity does increase during events, it affected by wind. As such, local adaptation strategies must be based on scenarios synergies potential changes