I've read many different reports regarding the weather in August. And yes, the weather is of course very unpredictible. But can you tell me if it's most of the time is warm enough to not have to wear a jacket at night? We're going to be there around the 10th of August. I've read that it can be up to 90 degrees and humid? But other reports stated that it was cold and rainy too. So what do you think about dressing at night?

It hardly ever gets below 10C (50F) at night, average minimum would be about 12C (54F). Check out http://www.weatheronline.co.uk/Europe.htm

Those tha worry about "unbearable" heat are unable to open a window.

Unbearable heat is 85 degrees in the hotel room with high humidity. Just opening a window in a room without cross-ventilation doesn't cut it.

Then buy a fan, but make sure it is dual voltage and has a plug that fits.

39.5° in August 2003.
About 15° in August 2007.

You can get past weather averages at www.weather.com or www.wunderground.com

Like stocks, past weather stats "do not reflect future performance".