Shifts of the air temperature in Latvia from 1991 to 2020

Evidence of the climate changes are evident in all regions of the world. In this study we examine the air temperature variability in Latvia during the last climate normal (1991-2020) in comparison with the previous two climate normals (1971-2000; 1981-2010), as well reference period (1961.-1990) describing seasonal and regional changes. Over last 60-years (1961-2020), the annual mean temperature has increased by 1.2°C across Latvia, with largest increase (0.5°C) between the last two climate normals (1991-2020 and 1981-2010). Across Latvia, winter temperatures have risen more rapidly by around 2°C, while summer temperatures have risen by around 1°C. The study revealed a shift in climate types: in the western part of the country near Baltic Sea coast, climate zones have changed from boreal (Dfb zone) to temperate (Cfb zone) according to the classification of W. Koppen. In these areas, the coldest month (January or February) has an average air temperature above -3°C. The values of the continentality indices have also changed, with a decrease in the influence of the continentality effect, that is particularly strong in the eastern part of Latvia.