Cluj-Napoca has a warm-summer continental climate . The climate is influenced by the city’s proximity to the Apuseni Mountains, as well as by urbanisation. Some West-Atlantic influences are present during winter and autumn. Winter temperatures are often below 0 °C (32 °F), even though they rarely drop below −10 °C (14 °F). On average, snow covers the ground for 65 days each winter. In summer, the average temperature is approximately 18 °C (64 °F) (the average for July and August), despite the fact that temperatures sometimes reach 35 °C (95 °F) to 40 °C (104 °F) in mid-summer in the city centre. Although average precipitation and humidity during summer is low, there are infrequent yet heavy and often violent storms. During spring and autumn, temperatures vary between 13 °C (55 °F) to 18 °C (64 °F), and precipitation during this time tends to be higher than in summer, with more frequent yet milder periods of rain.
The city has the best air quality in the European Union, according to research published in 2014 by a French magazine and air-quality organization that studied the EU’s hundred largest cities.