The climate in Slovenia

Climate zone: Moderate zone of the northern hemisphere
The climate in Slovenia is quite varied, but generally does not offer extreme climatic conditions. It is cold, wet and some nice summer months are also present. A beach holiday can also be enjoyed in the warmer season, but water temperatures will not reach much more than 23 °C. The warmest and rainiest part of the country is Obalno-kraška. The coldest is Primorsko-notranjska. Due to the warmer temperatures the best time for traveling is from June to September. Less attractive are the cold months from November to March.

Temperature records of the last 47 years

The hottest temperature measured from 1975 to September 2022 was reported by the Ljubljana Bezigrad weather station. In August 2013 the record temperature of 40.2 °C was reported here. The hottest summer from July to September, based on all 2 weather stations in Slovenia , was recorded in 2022 with an average temperature of 21.1 °C. This average temperature will normally be measured every 4 to 6 hours, thus also including the nights. Normally, this value is 19.5 degrees Celsius. The average maximum daily temperature at that time was 27.3 °C.
The coldest day in these 47 years was reported by the weather station Ljubljana Bezigrad. Here the temperature dropped to -16.2 °C in January 2003. Ljubljana Bezigrad lies at an altitude of 298 meters above sea level. The coldest winter (January to March) was in 1985 with an average temperature of -1.1 °C. In Slovenia, it is usual to have about 4.3 degrees more at 3.2 °C for this three-month period.

Long-term development of temperatures from 1991 - 2021

In contrast to single record values, a long-term development cannot simply be brought about by all weather stations in the country. Both the number and the locations are constantly changing. A simply calculated average value would give a falsified result. If several measuring stations in particularly cold mountain or coastal regions are added in one year, the average would already decrease as a result of this alone. If a station fails during the summer or winter months, it does not provide any values and falsifies the average again. The subsequent long-term development was therefore reduced to only 1 measuring points in order to have actually comparable data over as long a period as possible.
In the years 1991 to 2021 there were only these 1 weather stations in the whole country, which reported continuous temperature values (Ljubljana Bezigrad). From these weather reports we have created a long-term development that shows the monthly average temperatures. The hottest month in this entire period was July 2015 with 24.4 °C. January 2017 was the coldest month with an average temperature of -3.2 °C.
The average annual temperature was about 10.8 °C in the years after 1991 and about 12.1 °C in the last years before 2021. So in less than 31 years it has increased by about 1.3 °C. This trend only applies to the selected 1 weather stations in Slovenia. A considerably more comprehensive evaluation of the global warming has been provided separately.

Data basis and methodology

The data of the individual measuring stations are based on the archives of the German Weather Service, individual values averaged and supplemented by own elements. In order to determine a representative national average, average values were first calculated for each part of the country, which were then summarized at the national level. Thus, if a disproportionate number of weather stations are located in a small area, their number does not affect the national average. There are 2 stations in Slovenia itself. In 10 cases, neighboring but nearby weather stations were also used to obtain more accurate values.