Power has been cut to more than 10,000 homes in Sydney’s west after a severe thunderstorm Sunday afternoon.

Endeavour Energy said the suburbs affected included Riverstone, Springwood, Emu Plains, South Windsor, Winmalee, Yellow Rock, Hoxton Park and Hinchinbrook.

Emergency crews are responding but have been unable to provide a timeframe for the repairs.

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The State Emergency Service (SES) was dealing with almost 400 calls state wide, while Fire and Rescue New South Wales was responding to almost 90 jobs on top of that in the Sydney Metropolitan area.

Earlier on Sunday, a warning was issued for damaging winds and large hail stones for much of the state including the Hunter, Illawarra and Central West Slopes and Plains districts.

The SES received nearly 90 calls for assistance earlier in the day, mainly for leaking roofs and fallen branches with some reports of localised flash flooding and hail.

This was the eighth straight day of thunderstorms across the state, which led to flooding and two helicopter rescues on the far south coast.

SES and NSW Rural Fire Service crews will remain mobilised for at least three more days as the pattern of hot and humid weather followed by thunderstorms continued, and they warned that evacuations may be necessary in some low-lying areas.

SES incident controller Ashley Sullivan said conditions on Sunday had not been as bad as expected, but warned NSW residents to remain vigilant in the coming days.

“We’ve seen the worst of the bad weather,” Mr Sullivan said.

“We may have some more thunderstorms. In fact we’re meant to see thunderstorms right through to probably Tuesday and Wednesday,” he said.

“But the worst of the severe storms would appear to be over, but we’re not out of the woods yet.”

#SydneyStorm | Severe thunderstorms packing heavy rain, large hail and damaging winds are moving over #Sydney NOW. pic.twitter.com/rkE3uYeOwN

— Australian News Net (@AusNewsNetwork) December 7, 2014

Hail looks like carpet of snow in Pymble. #SydneyStorm @702sydney @abcnews pic.twitter.com/e5Da8oHEJn

— Elysse Morgan (@ElysseMorgan) December 7, 2014

SES spokesman Phil Campbell said although Sunday’s storms were were not as bad as in previous days, NSW residents should continue to monitor the extreme weather.

“So a few things people can do just to make sure they’re ready for those storms is to make sure their gutters and down pipes are clear, secure and put away any loose items in their backyard, and make sure their roof is in good repair,” Mr Campbell said.

Heavy rain and flooding on the far south coast caused a major rescue operation when four people were winched to safety from a flooded river.

Two men, aged 49 and 56, and their 10-year-old daughters were on a canoeing trip on the Deua River, in the Deua River Valley, which began to rise after heavy rains.

The group activated their Personal Locator Beacon (PLB) at 2:00am (AEDT) on Sunday and a search was initiated.

At 7:00am (AEDT) a group of volunteer searchers found the group on a riverbank and the Westpac Lifesaver Rescue Helicopter was called to the scene and winched the group to safety.

Police were told that while their tents and canoes were washed away by floodwaters, no injuries were reported. All four people were from the ACT.

SES crews attend a flooding incident at Canterbury in Sydney during a major storm on Saturday night. Supplied: NSW SES

Police praised the group for taking their PLB with them.

“We recommend anyone embarking on a trip – be it bushwalking, canoeing, canyoning or similar – to take one of these Personal Locator Beacons with them,” far south coast duty officer Inspector Peter Volf said.

“Today’s event is proof they assist in rescue efforts in what can be high-risk scenarios.

“We would also recommend that local weather conditions are checked before venturing out,” Inspector Volf said.

In a separate incident on the south coast, the helicopter rescued a farmer in Bega after he was trapped by rising floodwaters while herding cattle.

Stephen Leahy from from Westpac Lifesaver Rescue Helicopter said airlifting was the best option in both rescues.

“There was certainly potential that emergency services would have to use boats but ultimately this was the quickest, fastest and safest method,” Mr Leahy said.

Residents on the far south coast who live in low-lying areas were warned to be ready to evacuate as river levels rise.

“Evacuations are possible, and you’ll see our volunteers out and about in Bega in particular, and up in Moruya conducting reconnaissance and doorknocking,” said SES spokesman Ashley Sullivan.

The Bureau of Meteorology issued flood warnings for three rivers in the south of NSW.

Up to 250 millimetres of rain fell over the Moruya River valley since 11:00am (AEDT) on Saturday.

A flood warning was also issued for the Bega River for minor flooding at North Bega after 153 millimetres of rain fell in the 24 hours to 8:00am (AEDT) today.

And the Snowy River had rainfall totals of 57 millimetres since 9:00am (AEDT) on Saturday, and a further 10-20 millimetres forecast for Sunday.