Hot bucket of water in freezing weather will not work.
I had boiling water yesterday, id mop the windows up, go to blade them and theyd be frozen.
Anti freeze is a no no apparntly.
Get screen wash, the concentrate stuff works up to -15 apparntly and its very suds so great for cleaning.
Halfords doing 3 for 2, i bought 3 x 5l concentrate for £9 i think. used some in bucket neat today, i diluted it down a bit cause was very suddy.