The temperature in Germany during the summer is usually warm during the day (75-80 degrees Fahrenheit) and cooler in the evening. Germany can experience relatively cool spells (65 degree high during the day). You should pack a warm sweater for the evening and cool days. Bring clothes that you can layer for ease of comfort. Freiburg is known to be in the warmest and most sunny region of Germany, however there may be some afternoon rainstorms so a light parka or an umbrella is essential.
• Weather.com http://www.weather.com
• CNN's Germany Weather Page http://weather.cnn.com/weather/forecast.jsp?locCode=TTPP