Paramedics responded about 15 minutes later to reports of storm damage to a house on Limekilns Road, Clear Creek.
They assessed two patients, a man who had suffered cuts to the face and was treated at the scene, and a woman who had suffered back and neck injuries who was taken to Bathurst Hospital in a stable condition.
NSW Ambulance Inspector Meah Ferguson said the Meadow Flat man was lucky to have escaped with relatively minor injuries.
"It's not every day you get called out to a tornado and this one packed quite a punch," he said.
"When we arrived on scene we found extensive damage to the patient's dwelling and surrounding areas."
Bureau of Meteorology senior meteorologist Jackson Browne said the low-pressure system created a "special breed" of rotating thunderstorms that can generate tornadoes.
Meanwhile, patches of the state's Riverina region near Temora and Griffith have been hit by giant hailstones about 6 centimetres in diameter, Mr Browne said.
It's the second day NSW has had severe thunderstorm activity develop across the state, with damaging winds and heavy rain leading to some flash flooding.
The weather is fuelled by a vast "supercell" low-pressure system which has moved from the west of the country, through SA and into eastern Australia, where it now stretches from Tasmania up to Longreach in southern Queensland.
"The more severe aspects are over NSW and southern QLD … There's a really large low pressure system and associated trough that's sitting over the western slopes and inland planes of NSW," Mr Browne said.
The bureau has issued a warning issued for another storm cell over the Sydney basin, which Mr Browne said was moving in from Richmond on the city's western fringe and making a beeline for the airport.
Most of NSW is now under a thunderstorm warning.
On Friday, meteorologists expect the bulk of the trough to move up to the northeast of NSW and Southern Queensland.
"There's a chance Sydney could see some severe thunderstorms on Friday," Mr Browne said.
"On Saturday, the main trough and low move out into the Tasman Sea, however we do still have some storms that will persist, but thankfully it's very unlikely the storms will be severe."
Residents in Sydney, Brisbane and Canberra have been encouraged to brace for heavy rain, strong winds and hail, with flash flooding also a concern.
Earlier on Thursday, Weatherzone meteorologist Esteban Abellan said residents in NSW, the ACT and Queensland should prepare for severe storms and flooding.
"A deep trough is moving over eastern NSW and eastern Queensland and it's moving very slow, which means it is going to generate severe weather today and tomorrow," he told NCA NewsWire.
"Large hail, heavy remain and damaging wind gusts should be reaching the coast later in the day in Sydney, while afternoon storms should also be firing up in Canberra and Brisbane."
The storms are expected to be felt across much of the east coast but northern NSW and Queensland are expected to be hit the hardest.
The Bureau of Meteorology is predicting up to 45mm of rain to fall in Brisbane across Thursday and Friday.
Large parts of Victoria can also expect heavy rain, as well as eastern Tasmania. Rain in Victoria is set to last into next week.
The same supercell wreaked havoc in Adelaide on Tuesday and Wednesday, which was drenched by heavy rain and massive hail from Barossa to Balhannah.
About 50mm of rain fell between 1pm to 2pm at Mount Lofty on Wednesday.
