Slovakia belongs to the northern moderate climatic zone, with four seasons. The weather in Slovakia changes a lot by the influence of dry continental air from the west and the humid ocean air from the North, Baltic and Mediterranean Sea. The topography of Slovakia is very diverse and the altitude is also an important factor affecting the air temperature, rainfall, solar radiation and wind.
The weather is usually warmer in the plains than in mountainous areas. The warmest and driest region of Slovakia is Podunajská nížina (Danube lowland) with an annual average temperature around 10.3 °C and precipitation around 530 mm. With increasing altitude the temperature decreases and the rainfalls/snowfalls increase. The coldest places are mountain peaks in High and Low Tatras with the average temperature of -4 °C in Summer and -10 °C in Winter with precipitation over 2000 mm.
Each season (Spring, Summer, Autumn and Winter) lasts three months. The dry continental air brings in the summer heat and winter frosts. In contrast, oceanic air brings rainfalls and reduces summer temperatures. In the lowlands and valleys fog is often, especially in winter.
Spring starts with the 21st of March and is characterized by colder weather with average daily temperature of 9 °C in the first weeks and about 14 °C in May and 17 °C in June. In Slovakia, the weather and climate in the spring is very unstable.
Summer starts on 22nd June and is usually characterized by hot weather with daily temperatures exceeding 30 °C. July is the warmest month with temperatures up to about 37-40 °C, especially in regions of southern Slovakia – in the urban area of Komárno, Hurbanovo or Štúrovo. Showers or thunderstorms may occure because of the summer monsoon called Medardova kvapka (Medard drop – 40 days of rain).
Autumn in Slovakia starts on 23rd September and is mostly characterized by wet weather and wind, although the first weeks can be very warm and sunny. The average temperature in September is around 14 °C, in November to 3 °C. Late September and early October is a dry and sunny time of year (so-called Indian Summer).
Winter starts on 21st of December with temperatures around -5 or -10 °C. In December and January it is usually snowing, these are the coldest months of the year. At lower altitudes, snow does not stay the whole winter, it is changing into the thaw and frost. In the mountainous regions, the land is mostly covered by snow and is typical with weather inversions when the cold air and fog remains in the valleys, while the temperature in the mountains is higher and the weather is sunny.
Major climatic regions of Slovakia are as follows:
Warm regions – Climate of lowlands – extend up to 400 m above the sea level with an average temperature of 8-10 °C and annual rainfall 500-750 mm. The average monthly temperature in January is -1 to -3 °C. Number of summer days with a temperature of 25 °C and higher is 50. This kind of climate occurs at Záhorská Lowland, Podunajská Lowland and Východoslovenská Lowland. It is the typical climate of the capital city Bratislava or the second largest Slovak city Košice.
Slightly warm regions – Climate of basins – highlands and mountains with lower altitudes, around 700-800 m. Average annual temperatures vary between 4-8 °C, average July temperature falls below 16 °C. The annual rainfall is 600-1200 mm. Number of summer days in the year is less than 50. This climate can be found in almost all basins in Slovakia. For example Podtatranská basin, Žilinská basin, Turčianska basin, Zvolenská basin. It is the typical climate for the towns of Poprad and Sliač.
Cold regions – Mountain climate – characterized by the July average temperatures below 16 °C. The average annual temperature is between -3 and 4 °C. The average monthly temperature in January is -10 °C and 4 °C in July. Annually, the rainfalls are between 800-2000 mm. Most of the region is forest and grassland. This kind of climate occurs in mountains and in some villages in the valleys of Orava and Spiš.
- Štúrovo – the warmest area, with an average annual air temperature 10.4 ° C
- Bratislava – the highest annual average air temperature 12 ° C (in 1992) and the largest temperature difference in the night of 31st December 1978 to 1st January 1979 – in 6 hours, the air temperature dropped 20 ° C and during the next 10 hours another 10 ° C (30 ° C in 16 hours).
- Bratislava (Petržalka) – the highest average monthly air temperature 26 ° C (August 1992)
- Komárno – the highest measured temperature 39.8 ° C (5 Jul 1950)
- South Slovakia – the highest daily average temperature 30.2 ° C (8 July 1957) and the longest period of tropical days (above 30 ° C) from 21 July to 11 August 1994.
- Starý Smokovec – the coldest area with an average annual temperature of -3.7 ° C
- Starý Smokovec (Lomnický Peak) – the lowest average annual temperature -5.2 ° C (in 1956) and the lowest average monthly temperature -18.1 ° C (February 1956)
- Starý Smokovec (Štrbské Pleso) – the longest duration of winter, it lasts 204 days
- Vígľaš (Zvolenská kotlina) – the lowest measured air temperature -41 ° C (11 February 1929)
Average annual rainfall for the whole of Slovakia is 743 mm. Approximately 20% of the total annual precipitation total falls in the form of snow.
- Starý Smokovec (Zbojnícka cottage) – rainiest part of Slovakia with an average yearly rainfall of 2130 mm and absolutely the highest rainfall of 3229 mm (in 1958).
- Salka – the highest daily rainfall 232 mm
- Senec, Pusté Úľany – the driest area with average annual rainfall – 483 mm
- Trebišov – absolute lowest rainfall in the year 1917 (283 mm)
- Low Tatras (Chopok) – the most windy place with an average annual wind speed 9.5 m/s (34 km/h)
- Starý Smokovec (Skalnaté Pleso – Rocky Mountain Lake) – the highest measured wind speed 78.6 m/s (283 km/h)
- Hurbanovo – the most sunny place in Slovakia – average 2190 hours of sun per year (the maximum quantity of sunshine was 4 447 hours)
- Trstená, Orava – the least sunny place – only 1052 hours of sun per year