It shut down schools, caused power outages, train delays and the highway to close, but no-one really seemed to mind as a winter wonderland took over the Mountains with heavy snow falling above 700 metres from Thursday evening.
Mayor Mark Greenhill officially declared it "snowball day" as tourists and locals flocked to towns above Wentworth Falls to take in tobogganing, a snowball fight, some even skiing down snow-laden streets.
Snowfall totals were about 10-15 centimetres for Katoomba and Wentworth Falls, and there were similar falls for Orange and Oberon further west on the Central Tablelands, said Anthony Duke, a meteorologist with Weatherzone.
But what brought the alpine, ski resort-style conditions?
The Bureau of Meteorology said the cold snap was because of an east coast low pressure system off the Illawarra coast and a high pressure system over the Great Australian Bight.
"Those two systems, the high and the low, combined to direct a deep cold southerly stream over south-eastern Australia," a spokesman said.
"Coming from the latitudes around Tasmania and south of it, this cold air of Antarctic origin [has come] across alpine areas into central and northern parts of NSW."
Homes in the Upper Mountains were hit with power outages on Friday morning. Endeavour Energy worked to repair the damage from the heavy snow-laden branches falling on power lines, after losing transmission at the Blackheath sub-station.
Some 5500 homes were without power through Friday and at the height of the snowfall at 7.30am - 4000 at Blackheath, 1155 in Katoomba, 655 in Mt Victoria and 104 in the Megalong Valley.
Endeavour Energy spokesman Peter Payne said the majority of homes had the power back on by 1pm Friday after the company was able to patrol the 15km of affected power lines.
The Blue Mountains State Emergency Service co-ordinated the snow operation with the Rural Fire Service and police, managing multiple snow rescues from cars on Thursday night between Katoomba and Blackheath.
SES incident controller John Hughes said: "Our biggest thing was checking on the safety of stranded motorists on Thursday night. We assisted 50 people mainly between Katoomba and Blackheath who spent the night at Medlow Bath RFS."
"Some people came out of their houses and tried to drive and got stuck. Friday night was still icy," he said.
SES was also busy assisting Katoomba hospital staff to get to work, transporting 20 of their staff to and from the building in "half a dozen borrowed SES vehicles from Sydney".
Twenty-three people were treated at Katoomba Hospital with "snow-related injuries ... [injuries to the] limbs, neck and back with one minor head injury", a spokeswoman said.
"We had to get the ones who had done the nightshift home on Friday morning and bring the new shift in. The hospital being a critical facility we had to get the staff in."
Mr Hughes said winds were only 40km and it was lucky there was no "significant damage caused ...the damage may have been much more severe".
Traffic delays ensued for snow seekers over the weekend, with the Great Western Highway from Katoomba closed to traffic on Saturday morning due to black ice and dangerous driving conditions.
Blue Mountains Police Superintendent Darryl Jobson said driver safety was the paramount concern of police.
From Thursday evening to Saturday afternoon, the snow storm and associated cold weather caused significant disruption, particularly to drivers using the GWH which was closed at various times. "We had a number of trucks that 'jackknifed' and other vehicles slid from the roadway due to icy conditions and there was no alternative but to close the highway," he said.
At Mt Boyce, just west of Blackheath, the temperature dropped below zero at 10.30pm on Thursday night and by 5am Friday was as low as -1.4. But by 9.30am it was slowly warming up to deliver milder conditions for snow seekers. By then the temperature at Katoomba was 1.4c, and snow had been falling for 12 hours.
The snow hung around on the ground for the weekend in parts of Katoomba and higher up. Blackheath still had snow on the ground on Monday.
Blue Mountains mayor Mark Greenhill declared Friday, July 17 a "snowball" day and most Upper Mountains schools shut, as well as many schools further down the Mountains because staff couldn't get into work.
The train line remained operational throughout the weekend but some services were cut or reduced. With roads still shut due to black ice, those travelling on trains faced the added problem of trackwork.
Mr Hughes said the local emergency management committee endorsed a Blue Mountains snow plan in March.
"We were planning a snow exercise in August. Now we'll have a debrief instead, generally it went pretty well."
