Destination not hotter than 25 degrees celsius [closed]

I search for a destination where the weather in summer is not hotter than 25 degrees celsius (let it be 29 at maximum). Being exposed to a hot environment causes problems for my immune system. As I have the ability to work remotely, I would consider travelling for about half a year while working and then returning to where I actually live (central europe).

My native language is German (German citizen) and my English as well as my Russian skills are quite good. The only requirements in this case would be:

• internet connection
• no city prohibiting foreigners to enter (Norilsk in Russia for example)
• number of inhabitants should be more than 50 000