It has been 73 years since Sydney has become so cold, so suddenly this early in the year, prompting residents to crank up the heating a bit earlier this year.
The average minimum temperature for the past week (to 7th May) has been 11.3 degrees, down from 15.6 degrees from the previous week.
This sort of cold typically arrives later in May. In years when it has become colder earlier than this year, most recently in 2009 and 2008, the cooling has been more gradual.
The last time it has become as cold as now as early and as suddenly as this was in 1941.
In 1941 it was the week from 26th April to 2nd May when the city averaged a minimum of 10.9 degrees, down from 15.2 degrees the previous week.
The typical home in the eastern suburbs or north shore has now cooled down to only 16 degrees from a balmy 20 degrees only a week ago. Blankets, doonas, flannelette pyjamas and hot water bottles are all getting plenty of use.
Last weekend a strong front sent a pool of cold air from Antarctica across southeastern Australia then early this week another front maintained the chilly southerly winds for a few more days.
Looking ahead, winds will turn from southerly to easterly in the next few days, blowing off a relatively warm ocean. Then this weekend a low pressure trough and front crossing from the west will cause wind to turn northerly, bring in some cloud, moisture, some rain and a bit of wind. All of this will add up to warmer nights for the next week or so.