10-20 mm of snow is only 1/2-1 inches.

People would barely notice that here. I often don't even bother to shovel such a piddling amount, although I did shovel the porch yesterday of about that amount that came Saturday. Threw out some salt too. The snow becomes ice and gets slippery when it is really cold.

This morning it was 6F - about -14C.

It was close to 50F a few days ago though.

Must not snow much in London.