It's a freezing Friday afternoon in Sydney by December standards, after the morning dawned clear and sunny with the promise of a warm, sunny end to the working week.

But things changed very rapidly just before midday, as a line of storms encircled the city from the south and west.

The storms soon moved across the city, combining with a southerly change and lingering showers to send the mercury plummeting in all suburbs.

• Between 11:30 am and 12:30 pm, Sydney (Observatory Hill) dropped from 21.2°C to 14.4°C.

Image: Sydney's temperature and rainfall observations during the last 24 hours, showing a rapid temperature drop around midday on Friday.

Temps fell to even lower levels at weather stations all across the city. For example:

• It was just 13.1°C at 1 pm at Terrey Hills on the northern beaches.
• Temps fell to just 14.1°C at midday in Richmond in the city's far northwest.
• Holsworthy, in the city's southwest, copped the storms earlier than most other suburbs and fell to just 12.3°C at 11:18 am.

Small hail and loud grumbles of thunder were reported in many suburbs with the onset of the storms, but a gloomy rain has now set in as we write this story.

Not sure whether you’d bat or bowl - Clark Reserve Kearns/Raby #SydneyStorm pic.twitter.com/7sFN4YhgwO

— Craig The Speculator (aka The Raby Talker) (@craigspeculator) December 10, 2021

Around 2 pm on Friday afternoon, it was still pretty miserable in Sydney with temperatures not much warmer than 15°C in most suburbs. To put that into perspective:

• Sydney's average daily maximum in the coolest month, July, is 16.4°C.
• The coldest December maximum on record was 15.2°C back in 1957. Today won't come close to breaking that record because, as mentioned, it had already reached 21.1°C earlier in the day, and could again possibly reach or even exceed that sort of temp later today.
• Newcastle, barely two hours north of Sydney, reached 24.1°C at 1:50 pm, with storms yet to penetrate that far north.

All indications are that the rain should clear from most Sydney suburbs by mid-afternoon and the weekend ahead should be mostly clear but cool, with tops around 23°C.