Summer starts here in Australia in a month from now. (We'll then be contending with the return of bushfires.)
I think it's disservice to assert the weather is what will keep our case count low -- when a lot of people have gone through a whole lot of shit (and still are) to achieve & maintain the situation we now have.
I think there's sufficient contra-examples in both hemispheres to suggest that the weather is not a major factor -- though it is politically expedient & convenient to point at the weather to distract from mismanagement.
I'm not a politician, I'm not a nationalist, my birthplace is not the culture which I've been raised under, where my parents come from I've never lived and where I live now I have no ties whatsoever, so simply I don't care about country politics and trying to suggest anything different is the real disservice.
It's a fact that warm weather plays a huge role. In Europe we have seen a first relief during Spring and all countries have seen a huge dip in cases during their warmest summer months, completely irrespective of the countries individual measures. That's just a hard fact that you can't argue away in good conscience.
Furthermore, irrespective of how well countries have done, how many sacrifices people have done and what measures countries have taken (e.g. Germany vs. Sweden vs. UK vs. Czechia, etc.) all European countries see the same acceleration of cases. The only difference is the baseline where the spike starts, but the curve upwards is literally identical, so it further underlines that the weather has a bigger influence than any other measure except a full lockdown on the infection rate of coronavirus.
If people that repeat this claim, asserting it as fact, don't have citations -- then that's a different but related problem.
In Australia we got this under control through winter. Several states (South Australia, Western Australia, Tasmania, Northern Territory) had it so well controlled they had little if anything resembling strict lockdowns. Also through winter.
If 'all of Europe' (I'm not sure if you're talking mainland only there, or are including the very warm bits down the south, etc) is having the same results, then absent a control set to compare to, we can't know if that's an effect of comparable politics / culture, lack of controlled border controls, that a tipping point has been reached, or, as you say, 'because it's cold'.
Given that we have a lot more measures in place now (masks, distancing etc), something else has to play a role. February and March were unusually warm and sunny. I don't know whether that's relevant, but it seems unlikely that the counter-measures predict the peak - they are much stricter now than they were at the beginning of the year.
The current assumption in Norway, based on testing and WHO guidelines) are that we detect about 1/2 of the active cases through testing now, compared to 1/10 back in March. Applied to your numbers, the current outbreak in Germany is about a fifth of what it was back in March.
Be careful about assuming the numbers represent the same thing over time and between countries; in general the ratio of positive cases compared to the number of tests has changed a lot during the last eight months.
Some of the reports from the Norwegian health authorities has explicit notes about where reporting and testing criteria changed during the timeline.
From what I understand the current daily test capacity for Germany is about twice as large as it was in April. I do believe that they're still only testing those who exhibit symptoms or have been in contact with somebody who tested positive.
Speaking of test positivity, their all-time high is 9% and the most recent week for which information is available isn't that far off that at 5.6%, and I think that number's effectively a week old at this point. All indications are that Germany really, genuinely does have a bigger outbreak this time around.