The article presents a climatological dataset from the Polish Polar Station Hornsund (SW Spitsbergen). With a positive trend of mean annual temperature of +1.14 °C per decade during 1979–2018, the climate in Hornsund is warming over 6 times more than the global average. Due to a general lack of long-term in situ measurements and observations, the High Arctic remains one of the largest climate-data-deficient regions on the Earth. Therefore, the described series is of unique value.