In most of Germany, the climate is moderately continental, characterized by cold winters, with average daily temperatures around 0 °C or slightly above, and warm summers, with maximum temperatures around 22/24 °C in July and August.
The northernmost area (Bremen, Hamburg, Lübeck, Rostock, Kiel) is slightly milder, but it's also rainier and windier because of the influence of the Atlantic Ocean. The massifs of south-central Germany and the small portion of the Alps in the far south have a mountainous climate, which becomes of course colder as altitude increases.
Being that Germany is exposed to both mild air masses from the Atlantic Ocean and cold air masses from Russia or the North Pole, the weather is often unstable, with remarkable changes and different meteorological situations, such as cold, heat, wind, fog, snow, and thunderstorms.
During winter, snowfalls are quite frequent though generally not abundant (except in Bavaria and in the mountains, and sometimes in the north-eastern plain). Snow is more common across the eastern belt, from Bavaria to the plains of the former GDR and up to the Baltic coast, while it is rarer in the western part, from the Rhine corridor to north-west exposed to the North Sea.
During cold waves from Siberia, temperatures can plunge to -15/-20°C in much of Germany, but these periods usually last for a few days in the north and central part, while they tend to last longer in Bavaria, where cold air stagnates with more ease. Snowfalls often occur after a cold wave, when the winds from the Atlantic begin to blow again. Later, with the persistence of the westerlies, the temperature rises further and the snow turns into rain.
When the westerly winds blow more intensely, they can bring fairly mild weather even in winter, with highs around 10/12°C in much of the country (except in mountainous areas).
In spring, the temperature rises slowly in March, which is usually still a cold month, with average lows around freezing, while highs are around 8°C in Hamburg, 9°C in Berlin and Munich, and 11°C in Frankfurt and the western areas. In April, daytime temperatures range from 12/13°C in Hamburg and Berlin to 15°C in Frankfurt. While Frankfurt and the western regions can more easily experience the first mild days, at other times, late cold spells typical of spring can occur, which come directly from the north and pass quickly over the plains of Germany, and are felt especially in Bavaria, where they cause snow showers with a higher frequency. In early April, short snowfalls with night frosts are still possible, especially in Munich and in Bavaria.
In spring and autumn, in the Alps and in the valleys of Bavaria, the Föhn, a southern warm wind that descends from the mountains and brings sudden increases in temperature, may blow, causing the rapid melting of snow, if present. This phenomenon is rarer in winter, when the wind doesn't blow from the south.
By the second half of April, the weather becomes a bit milder, and in May, when the average maximum temperature is around 18/20°C, the first warm days occur, which in Germany are characterized by possible thunderstorms in the afternoon, especially in inland areas.
The German summer, although it often brings pleasant temperatures, is not very sunny. In fact, in this season there are cool and rainy days, when Atlantic disturbances move over the country, alternating with periods when a high pressure system affects the country. In the latter situations, the days begin with clear skies and can even be hot around mid-day, while thunderstorms often form in the afternoon. These thunderstorms are less frequent in the northernmost region, which, however, is cooler and may experience more frequent rains due to disturbances coming from the Atlantic Ocean. Anyway, on warmer days, in Berlin and other cities that are not located near the coast, the temperature can reach 30/32°C or even more.
In fall, September is usually a pleasant month, but later the weather becomes progressively colder and rainy, with the first mists as well. In addition, the wind can be strong, especially in the northern areas. In November, the sun rarely shines; by mid-November, it is practically winter, and the first snowfalls are possible.