According to the Köppen climate classification, the city has a Mediterranean climate, bordering on a semi-arid climate (BSk), observed on the periphery of the region. Its average annual precipitation of 450 mm is due to the Pindus rain shadow drying the westerly winds.

However, the city has a summer precipitation between 20 to 30 mm, which increases gradually towards the north and west, turning some parts of the city humid subtropical.

Winters are somewhat dry, with common morning frost. Snowfalls occur sporadically more or less every winter, but the snow cover does not last for more than a few days. Fog is common, with an average of 193 foggy days in a year. During the coldest winters, temperatures can drop to −10 °C. The record minimum temperature in Thessaloniki was −14 °C. On average, Thessaloniki experiences frost (sub-zero temperature) 32 days a year.

The coldest month of the year in the city is January, with an average 24-hour temperature of 5 °C. Wind is also usual in the winter months, with December and January having an average wind speed of 26 km/h.

Thessaloniki’s summers are hot and quite dry. Maximum temperatures usually rise above 30 °C, but they rarely approach or go over 40 °C; the average number of days the temperature is above 32 °C is 32. The maximum recorded temperature in the city was 44 °C.

Rain seldom falls in summer, mainly during thunderstorms. In the summer months Thessaloniki also experiences strong heat waves. The hottest month of the year in the city is July, with an average 24-hour temperature of 26 °C.