Frankfurt has a temperate-oceanic climate . Its average annual temperature is 10.6 °C (51.1 °F), with monthly mean temperatures ranging from 1.6 °C (34.9 °F) in January to 20.0 °C (68.0 °F) in July (Data from between 1981 and 2010)
Due to its location at the northern tip of the Upper Rhine Valley in the Southwest of Germany, Frankfurt is one of the warmest and driest bigger German cities together with cities like Darmstadt, Mannheim, Karlsruhe and Freiburg im Breisgau. Summers in Frankfurt can get very warm, when compared to the rest of the country. Between the years 1981 and 2010 there have been 52 days in Frankfurt with a maximum temperature over 25 °C and 13 days with a maximum over 30 °C on average per year.
Climate change elevates the number of hot days. In the year of 2018, there have been recorded 108 days with a maximum of over 25 °C and 43 days with a maximum of over 30 °C (compared to 52 and 13 days on average per year between 1981 and 2010). The overall tendency for higher temperatures can be seen when comparing the climate data from 1981 to 2010 with the data from 2010 to 2020. It is getting sunnier, drier and warmer.
Being an urban heat island, Frankfurt is sometimes affected by tropical nights, where the temperature does not drop under 20°C between May and September. This occurs because the density of the city causes it to store all the heat.
The growing season is longer when compared to the rest of Germany, thus resulting in an early arrival of springtime in the region.
Winters in Frankfurt are generally mild or at least not freezing with a small possibility of snow, especially in January and February but dark and often overcast. Frankfurt is, on average, covered with snow only for around 10 to 20 days per year. The temperatures fell at about 70 days under 0°C and daily maximum has stayed under 0°C for about 13 days on average per year between 1981 and 2010. Some days with lows under -10 °C can occur more often here than at the coasts of Northern Germany, but not that frequently like in Bavaria or the eastern parts of Germany.
Because of the mild climate in the region, there are some well-known wine regions not far away such as Rhenish Hesse, Rheingau, Franconia (wine region) and Bergstraße (route). There is also a microclimate on the northern bank of the River Main which is responsible for palms, fig trees, lemon trees and southern European plants growing in that area. The area is called the “Nizza” (the German word for the southern French town Nice) and is one of the biggest parks with a Mediterranean vegetation north of the Alps.