I put them outside, in heavy rain there is water coming in. In light rains, this does not seem to be the case.

Not really. Water collects on the lid because it has edges; and then the water gets in.

I have them all outside on the balcony, but they are somewhat protected there. I haven't had any problems in stronger weather so far, but I don't know what it looks like when they are completely outside, for example in a garden.