Where in Finland are you located? I live in Western NY where we have a humid continental climate which is similar to the very southern tip of Finland. Once you start going north you run into a subarctic climate.
With that being said, I stored a number of computer components in my parents barn for a few years. While the items were safe from wind and precipitation, they were not safe from temperature. Almost all hard drives I had are now dead. Surprisingly, most if not all 3.5 and 5.25 floppy disks still work, go figure. I did not store any monitors, but I did store motherboards, floppy drives, cables, cases, joysticks, i/o cards, and so far they're working fine after taking them all out of storage after a number of years.
Keep hard drives inside. If I had to do it again, I'd find a climate controlled storage locker.
Hope this helps.
Searching for a Packard Bell 15" CRT Monitor - 1511SL or 1512SL