Weatherzone meteorologist Brett Dutschke said that as of 12pm Sunday, the ACT had received about 43 millimetres since the rain began on Saturday morning, but more was still to come.

"We're probably only halfway there before the rain moves away," he said.

"It is unusual … the last time there was heavier rain was last winter.

"In August there was 31mm in a day and Canberra has picked up a bit over 28mm in a day this time."

"To get intense rain for this long hasn't occurred since early winter, late autumn [last year]."

As of 7pm Sunday, the ACT SES had received 159 calls for help due to the wet weather since Saturday.

"The majority of jobs have been leaking roofs, collapsed ceilings due to water inundation and fallen trees. All six ACTSES units are responding to calls for help and are reducing the immediate risk of danger to residents and damage to homes. ACT Fire & Rescue is also providing assistance," the Emergency Services Agency said in a statement.

Flights in Canberra were impacted by the wild weather that battered Sydney on Sunday, with a Qantas flight from Hong Kong to Sydney forced to divert to Canberra Airport to refuel on Sunday.

Passengers travelling to or from Sydney were advised to check their flight status online, with a Qantas spokesman saying the airline was experiencing delays and cancellations because of the severe Sydney weather.

Virgin Australia cancelled four flights between Sydney and Canberra due to Sunday's weather.

Mr Dutschke said another 40 to 50 millimetres of rain was expected to fall on Sunday afternoon and night until the weather began to clear from Monday morning.

"By the middle of the day it should dry out, but there's still a chance of some showers even from late [Monday] into Tuesday but they'll only be fairly brief and light," he said.

And although the end of rain might be welcomed by some tired of struggling with an umbrella, the drier weather will cause temperatures to drop with daily maximums unlikely to reach 15 degrees for the rest of the week.

"Among all this rain it's stayed relatively mild because the winds have been blowing off a relatively warm ocean, but then the wind is going to change direction … it's going to turn more south westerly," he said.

"It's a fairly cool wind so even though we'll get a bit more sunshine during the day and long dry spells it's going to be colder."

Cloud cover will keep overnight temperatures slightly warmer.

Mr Dutschke said some of the wettest places in the region were Bega and Moruya, which had received about 170mm since Saturday, and Narooma and Ulladulla, which had been hit with about 160mm of rain.

All the coastal regions also had more rain too come.

"There's a chance of close to 100mm more for the Bega area but it should start to dry out [Monday] night, it's going to take longer to dry out than the ACT it's also where the focus is for the strongest winds in the region and damaging surf as well," he said.

Mr Dutschke said the wild weather on the coast would begin to clear from Tuesday when the intense low pressure trough and low pressure systems, which had brought down the most intense weather from northern NSW, moved away.

The treacherous surf conditions would take longer to subside while the wind continued and flood warnings were likely to remain current until at least Tuesday.

The Snowy Mountains and southern tablelands were also included in the severe weather warning for the coast.

While the wet yet warmer conditions dampened the potential for snow over the weekend, Mr Dutschke said there was a chance of snowfalls of between 5 to 10 millimetres in the Thredbo area later in the week as the wind changed and a cold front came through.

"There could be even a few flurries as early as Monday night, early Tuesday," he said.

The ACT ESA reminded people to stay clear of storm drains during the wet weather and call 132 500 for storm or flood assistance.

With Natasha Boddy

Weatherzone is owned by Fairfax Media, publisher of this website.