This is your warning to cancel all of your plans and go straight to bed after work.
Tonight's going to be bleedin' baltic, with forecasts hitting serious lows after a particularly cold one today.
Met Éireann had this much to say about it all:
Frost will become widespread tonight under clear skies and will be severe in many areas, except for Ulster where fog and cloud will persist.
Lowest values tonight 0 to -5 degrees generally, but 0 to +3 degrees over more northern counties. Fog will become more widespread overnight in the almost calm conditions.
Oh God, we're cold even reading that.
Wrap up warm kids, it's going to be a freezing one.