Air temperature changes until now

Hungary has a continental climate, with hot summers with low overall humidity levels but frequent showers and frigid to cold snowy winters. Average annual temperature is 9.7°C. Temperature extremes are about 42°C in the summer and −29°C in the winter. Average temperature in the summer is 27°C to 35°C and in the winter it is 0°C to −15°C. The average yearly rainfall is approximately 600 mm (1).

In central and western Europe, both the warm and cold tails of the temperature distribution in winter warmed over the entire 20th century. … Warming of winters during 1946-1999 occurred in both the warm and cold tails for both Tmax and Tmin, with the largest warming in the cold tail for Tmin. … There is more evidence for summer warming in the first half of the century compared with the second half (5).

The summer of 2012 was very hot and dry in South-East Europe; it was the hottest and third-driest on record in Serbia (8). For this part of South-East Europe (including parts of Northern Serbia and Southern Hungary, as well as smaller areas in Bosnia-Herzegovina, Croatia and Romania), the change of the likelihood of an extreme summer such as the one of 2012 between the decades of 1960-1970 and 2000-2010 was assessed. This was done by studying decade-long model simulations (general circulation model and an embedded dynamical regional climate model) and observations. From this study it was concluded that the magnitude and frequency of heat waves have increased considerably in South-Europe between the 1960s and the 2000s. In addition, indices combining temperature and precipitation to assess changes in dryness and heat stress risk have been analysed; these results also show an increase in return time, although the results are subject to uncertainties (9).

Urban heat island

For Budapest, the urban heat island intensity has been quantified from satellite data covering the period 2001-2016. The highest intensities were found in the city centre: up to 5°C. As building density decreases, the urban heat island intensity also decreases (13).

The highest monthly average urban heat island intensity in Budapest was recorded in June 2018 at 5 °C, but there are years when the average SUHI intensity remains below 3 °C, even in the hottest months (16). Intensities are highest in the summer months. In February and March, when urban island intensities are lowest, the average urban surface temperature in Budapest can be lower than in the surrounding areas, forming an urban cool island (16).

From time to time, in Hungary during summer, due to the lack of precipitation and strong evaporation, the surface water supply becomes less and less and the rural areas become hotter than usual. As a result, the difference in temperature between the urban and the rural environment decreases and thus the urban heat island becomes less pronounced (16).

In the period 1981-2016, the average urban heat island intensity was 2.3 °C for Prague and 1.8 °C for Bucharest, and it exceeded 4 °C in 6-10% of the cases. The highest values occurred in August in both cities, when built areas still accumulate radiant heat during daytime and release it slowly during night, while the rural neighbourhood starts cooling more rapidly during longer nights in August. City enlargement, traffic increase and conversion of green areas into built up zones have constantly augmented the urban heat island intensity in both cities during the last decades (14). Both Prague and Bucharest will be at least 1 °C warmer by the middle of the century (15).

Precipitation changes until now

The annual precipitation amount significantly decreased in the 20th century. It is most significant during spring when the sum of precipitation is only 75% of the sum in the beginning of the 20th century. The summer precipitation amount did not change in the past 100 years. The autumn and winter precipitation decrease is 12-14%. The winter precipitation is the lowest in comparison to the other seasons (1).

In central and western Europe, significant increasing precipitation trends over the 20th century dominate in winter for both average precipitation intensity and moderately strong events. Simultaneously, the length of dry spells generally increased insignificantly (5).

It is problematic that the decreased amount of precipitation falls in a more intensive pattern which decreases the potential utilization of the water and increases the run-off, which increases the risk of floods (2).

Heat wave and cold wave changes until now

In the Carpathian Region (encompassing Croatia, Hungary, Slovakia, Czech Republic, Poland, Ukraine, Romania and Serbia), heat wave events have become more frequent, longer, more severe and intense over the period 1961 - 2010, in particular in summer in the Hungarian Plain and in Southern Romania (10). Cold wave frequency, average duration, severity, and intensity over this period, on the other hand, generally decreased in every season except autumn. In this study, a heat wave was defined as at least five consecutive days with daily maximum temperature above the long-term 90th percentile of daily maximum temperatures. Similarly, a cold wave was defined as at least five consecutive days with daily minimum temperatures below the long-term 10th percentile of daily minimum temperatures (10).

The trend analysis shows a general tendency to more frequent, longer, more severe and more intense heat wave events in every season in the entire Carpathian Region. On the other hand, the cold waves show a general tendency to less frequent, shorter, less severe, and less intense events (10).

The Carpathian Region and the Mediterranean area are the two European hotspots showing a drought frequency, duration, and severity increase in the past decades and in particular from 1990 onwards (11). When drought effects are exacerbated by heat waves or vice versa, such combination may cause devastating effects, as it happened in summer 2003 in Central Europe (12). 

Air temperature changes in the 21st century

The results of model calculations show a temperature increase in Hungary in 2040 compared with 1961-1990. This projected increase is 0.8 – 1.8°C on an annual basis. For the seasons slightly different results are obtained: for spring, summer, autumn, and winter, increases are projected of, respectively, 1.0-1.6°C, 0.5-2.4°C, 0.8-1.9°C, and 0.8-1.2°C (1).

The number of frosty days is expected to decrease in 2040, compared with 1961-1990, in all parts of the country, by 12-15 days. The areas at higher altitudes are expected to show a larger (more than 14 days in average) reduction, while the southern, lower areas are expected to show a smaller change. The number of frosty days shows a definite reduction tendency, which will decrease the heat consumption due to a higher average temperature and a shorter heating period. The number of days with heat alert shows an increasing tendency in 2040, compared with 1961-1990 (by 14 days in the southern regions of the country), and this will cause a higher cooling demand, thus higher energy consumption (1).

The largest temperature increase is expected in summer, and the smallest increase in spring. The expected summer warming of Hungary in 2071- 2100 compared with 1961-1990 ranges from 4.5-5.1°C (scenario A2) and 3.7-4.2°C (scenario B2). In case of spring, the expected temperature increase inside Hungary is 2.9-3.2°C (scenario A2) and 2.4-2.7°C (scenario B2) (6).

Projected spatial gradients of warming for summer and winter by the end of the 21st century show increasing values from north to south in the summer, and  increasing values from west to east in the winter; differences are between 0.4 and 0.8°C (6).

By the end of the 21st century, countries in central Europe will experience the same number of hot days as are currently experienced in southern Europe (3).

If no action is taken to reduce greenhouse gas emissions, annual mean temperature in central Europe may increase by 3-4°C (up to 4-4.5°C in continental regions and Black Sea region) by the end of the 21st century (4).

The part of Hungary from the centre to the south-east, characterised by a flat topography, has the highest temperatures and the lowest annual precipitation totals. For this part, the highest temperature increase, significant changes in the extreme temperature events (increase of the summer days and decline of the frost days), and the highest precipitation decline (or, at least, the lowest precipitation-increase ratios) have been projected for 2021–2050 and 2071–2100 compared with 1961–1990 (according to regional climate models under IPCC A1B climate scenario) (7). With respect to climate change, four main climate-region types have been distinguished (7):

1. the western hilly area, characterised by relatively low temperatures, relatively small temperature increase, little change in the temperature extremes, more humid conditions with higher precipitation totals but relatively small change rates regarding heavy rain events.
2. a west central corridor from the north to the south of Hungary, characterised by a moderate temperature increase, distinct changes in extreme temperature events, moderate precipitation totals that are projected to increase, but with moderate changes in extreme rainfall events.
3. a large area of Hungary, ranging from the centre to the south-east, characterised by a flat topography, with the highest temperatures, the highest temperature increase and significant changes in the extreme temperature events (increase of the summer days and decline of the frost days), the lowest annual precipitation totals and the highest projected precipitation decline (or, at least, the lowest precipitation-increase ratios), a growing concentration of rainfall and thus longer drought periods.
4. the north-eastern part along the Slovakian border, characterised by the lowest annual mean temperatures, the highest intraregional temperature variation and moderate precipitation totals resulting in more humidity when compared with the other continental regions.

Precipitation changes in the 21st century

The change in precipitation does not show such a uniform tendency: the models forecast small changes which are in most cases not significant (1). The annual precipitation sum is not expected to change significantly in this region (6). For the summertime, however, model calculations point at mean precipitation decreases over central Europe (3), and an increase of the frequency and intensity of the extreme weather events (2).

In 2071-2100 compared with 1961-1990, summer precipitation is very likely to decrease (also, slight decrease of autumn precipitation is expected) by 24-33% (scenario A2) and 10-20% (scenario B2). Winter precipitation is likely to increase considerably (slight increase in spring is also expected) by 23-37% (scenario A2) and 20-27% (scenario B2). The largest uncertainty of precipitation change is expected in summer (6).

In the reference period, 1961-1990, the wettest season was summer, then, less precipitation was observed in spring, even less in autumn, and the driest season was winter. If the projections are realized then the annual distribution of precipitation will be totally restructured, namely, the wettest seasons will be winter and spring, and the driest season will be summer (6).

References

The references below are cited in full in a separate map 'References'. Please click here if you are looking for the full references for Hungary.

1. Hungarian Ministry of Environment and Water (2009)
2. Hungarian Ministry of Environment and Water (2005)
3. Beniston et al. (2007)
4. Commission of the European Communities (2007)
5. Moberg and Jones (2005)
6. Bartholy et al. (2007)
7. Mezösi et al. (2013)
8. Hydrometeorological Service of Serbia (2012b), in: Sippel and Otto (2014)
9. Sippel and Otto (2014)
10. Spinoni et al. (2015)
11. Spinoni et al. (2013), in: Spinoni et al. (2015)
12. Fink et al. (2004); Ciais et al. (2005), both in: Spinoni et al. (2015)
13. Dian et al. (2020)
14. Zak et al. (2020)
15. Cheval et al. (2017), in: Zak et al. (2020)
16. Dezsö et al. (2024)