The city received 29 millimetres of rain to 9am on Friday, making it the wettest Christmas Day since 1942.

It fell just short of the 31.2 millimetres recorded in 1942 but well shy of the 40.4 millimetres that fell 127 years ago, the highest amount for 150 years since records began.

But it wasn't all doom and gloom for Sydneysiders, who were treated to temperatures of 28 degrees before the rain and as high as 33 degrees in the west.

The thunderstorms made their way through Sydney about 4pm and were most hazardous from 5.30pm until 11pm.

Mona Vale received the most rain, with 47 millimetres, while Avalon (44 millimetres) and Hornsby (40 millimetres) were also drenched.

During the storm, 8000 lightning strikes were recorded.

Boxing Day was a more subdued affair; temperatures were down slightly and any chance of an afternoon shower dampening family proceedings at the beach did not eventuate.

Weatherzone meteorologist James Casey said weather conditions will be more settled at the weekend, but precipitation is expected early next week leading into New Year's Eve.

"The weather coming up in Sydney will be nothing like yesterday [Christmas Day]," Mr Casey said. "There's still a chance of a few showers, around 1-2 millimetres for the rest of the week.

"We may have some heavier falls, but not like what we saw at Christmas."

According to Weatherzone, there is an 80 per cent chance of 10-20 millimetres of rain on Sunday, expected to fall north of Sydney, while temperatures this weekend will peak at 23 degrees as a result of overcast conditions.

New Year's Eve is forecast for a maximum of 25 degrees.

The SES said they responded to 198 emeregency calls on Christmas Day from concerned residents caught in the middle of strong rain and lightning strikes.