Sealing body cracks (water in trunk)

Hi Prius owners

So my windows started fogging a lot and there was water in the left side of the trunk, so I figured I will disassemble the rear interior and see what's happening there. Surprise surprise tons of condensation and it's nearing towards the rear seats by this time.

Typical problem I guess, though it's around 0 celsius (32 fahr) so the silicone would probably dry for a really long time, which is not acceptable as it starts raining/snowing quite often.

Question is - how big of a problem the non hot weather is? Would it suffice to put the car inside a parking slot with a roof above it for a couple of hours after applying the silicone? Any better ideas?

 

Darn that's a lot of things to consider, not as straightforward as just applying some silicone. Seems like the only sokution is a garage for at least abday or so and then some special silicone for faster drying in low temps. Will probably leave it for the pros then!