Berlin has a moderately continental climate, and summers are usually quite dry and warm here. There can be occasional heat waves but generally, the temperature is mild and comfortable all summer long.
July and August are the warmest months. However, nights can be cool. Atlantic depressions may bring a few rainy days or heat. Even if the weather is sunny in the morning, thunderstorms can break out in the afternoon, especially in the month of June. It is the wettest month of the year in Berlin with 70 mm of rain and ten rainy days on the average.