Where exactly are you going, OP?
Right now, you're catastrophising. We've all done it - I had one years back outside Nimes where the forecast was 36+ the whole time we were there, dicey aircon and two under 5. It turned out to be an amazing holiday because we adapted ourselves.
I know the Alps pretty well so I'll take your concerns in turn:
Temperatures: It's hot at the moment, just like everywhere. But it's rare to get tropical nights in the Alps so you get relief at night.
The current medium range forecast I've seen is for cooler temps from next week - where are you getting your forecasts from? Even Geneva is looking about ten degrees cooler next week.
Remember also the humidity is likely to be lower than here.
Thunderstorms: won't be all day. Are you reading the forecasts properly about rain/chance of rain? Again, which forecast are you looking at?
Rain: the great thing about the mountains is that you can often rise above rain in the valley. So if it's pouring at a lower altitude, it may be beautifully sunny elsewhere. A dreary day in the Valais might be gorgeous as you get up towards Bern. And the distances aren't huge.
Sleeping at night: Like I said, even right down in the valley most nights the temperature will drop. But also you do have portable aircon to take the edge off.
Scary driving: I've never found driving in Switzerland to be too bad, but public transportation is excellent if you're finding it tricky.