This work presents a high-fidelity spatiotemporal analysis of the urban
heat island (UHI) effect in Swiss cities during the last six years. The
entire alpine country is simulated at once using the COSMO model at 1.1
km resolution, validated against a dense national measurement network.
Additionally, the bulk parametrisation
TERRA\textunderscore URB is used to model the dynamical
and thermal effects of urban areas. The resulting data allows us to
perform the first comprehensive analysis over the entire Switzerland,
with a focus on the urban heat island effect with intra-urban and across
cities comparisons, and to report on the current state of urban warming.
Despite the medium-small size of the cities, the UHI is of considerable
magnitude especially when considering peak values in ideal weather
conditions. The present results confirm previous analyses performed for
individual cities, and shed new light on the country-wide picture by
highlighting features such as the marked seasonality of the UHI
intensity as well as the influence of local climate and topographical
features on the urban climate. A thorough discussion is also presented
highlighting the absence of simple relationships between UHI intensity
and bulk city parameters and weather patterns.