Summer is on in Germany, and folks are sweating up a storm. Pick up the German news and folks are already criticizing the Bahn trains because the AC just won't chill enough. Germans are sitting in the afternoons out in the beer parks, under umbrellas and trees....sipping chilled beer. You sit on the subway car and notice how many guys are wearing shorts to work. Road maintenance crews....you tend to notice they are all in shorts and some aren't even wearing shirts.
Germans aren't an air conditioning society....I must report. An American would arrive in June....find the temperatures a bit difficult, and then discover that most Germans don't have AC in the house or apartment. If they do have AC....it's likely a mini-unit and only chilling the living room, and only used for the afternoons.
Negativity? It's more of a thing about changing temperatures....walking from a cool place to a hot place, and Germans note this in the dramatic sense. They also add up electrical bills and would be furious to suddenly see their bills jump fifty percent when summer rolls around because of air conditioning costs.
As an American walking around Germany....it's a bit difficult to accept. Luckily, the days of heat are in your favor. In an average summer, there's probably only twenty days of extreme heat. And no....84 degrees is not considered extreme heat. You generally need to be 90 or more, to be in that category. You'd have to go back a decade to find a summer where there was sixty days or more of extreme heat. So it's a brief situation that you have to tolerate.
My advice for an American about to travel into Germany?
First, if you are traveling by train on a hot day....get on early in the morning and try to get to your destination by noon. Don't anticipate any of the modern trains will be able to chill much past 85 degrees. Afternoon temperatures on trains are the 'killer'.
Second, pick up bottles of water and sip on a hourly basis. Don't get into any stupid habits of drinking two or three German beers to re-hydrate yourself. From that drastic heat wave of a decade ago....French people were dropping like flies....mostly because they went to wine to re-hydrate, and drunk to extremes.
Third, you will likely discover this age old concept of sitting under a tree with a slight breeze. Make good use of that.
Fourth, take a look around and note casual dress attire by all Germans....even the ultra rich class. During the summer season....everyone dresses down a notch or two. Sandals are acceptable. Shorts are common. Ties aren't seen as much.
Fifth, you can ask for ice....but Germans don't put more than a piece or two into their drinks. Ice melts, and lessens the drink quality....Germans will let you know this if you ask.
Sixth, accept the fact that concrete buildings soak up heat. So as you sit in the hotel that lacks AC....you'd best hope for a fan in the room. That might be your only relief.
Seventh....if your surroundings are awful hot at 7PM....I'd strongly suggest to walk out onto the street and find a pub and simply enjoy a beer or two over the next three hours. It's usually cooler as the sun goes down, and the street area might be a relief.
Eighth.....remember that summer weather in Germany shifts day by day. You could easily awaken five days into a heat-wave....to find the temperature is now into the mid-60s, with stormy clouds drifting around, and a breeze which makes you wear a sweater in the evenings. If you are visiting higher elevations in Bavaria....you'd best expect some dramatic temperature changes over a twenty-four hour period.
Ninth, Germans will tell you that having something chilled is the best way to suffer through the circumstances. A glass of ice tea. A chilled beer. A cup of ice cream. These little things add up.
Finally, by the last week of August....you are on the verge of temperature change. People start talking fall....October-fest is around the corner....rain chills things a bit more often....and relief is at your doorstep.