The contrast couldn't be greater. The eastern US is experiencing record-breaking low temperatures while in Australia, the city of Sydney has had its hottest weather in nearly 80 years.
Posts on social media are reflecting what the extremes feel like.
The US National Weather Service (NWS) said the temperature in New York City had reached an all-time low for 6 January of -13C (8F).
Bitterly cold temperatures and dangerous wind chills will continue over the Northeast U.S. through Sunday. A moderation trend in temperature is expected to begin Monday and continue through midweek.— NWS (@NWS) January 7, 2018
Thousands of flights from the city's John F Kennedy airport were delayed by blizzard conditions, and other airports in the eastern US also suffered problems.
Thousands of people laying down on floor no space to walk and now water pipe broke down freezing water is all over ... sorry for the passengers— Aisha (@AishaKhan_1) January 7, 2018
Some travellers complained of being stranded on the tarmac in New York and facing long delays in baggage reclaim.
We’ve been on the plane itself for over 8 hours from Montreal (1 hour away). People are beginning to threaten to break open emergency exits and staff is still saying “30 more minutes” they’ve been saying this for hours. Something is up.— Chris Mendez (@thechrismendez) January 6, 2018
Passengers remain stranded at JFK airport: ‘It’s complete chaos’6000 flights cancelled: New York City https://t.co/FoYi3plnlV— skyshoes (@skyshoes) January 7, 2018
More than 1ft (30cm) of snow blanketed parts of US states including Massachusetts, Connecticut, Maine and New Hampshire, according to the NWS.
In eastern Canada, temperatures close to -50C (-58F) were forecast for northern Ontario and Quebec. Toronto airport has also experienced delays and cancellations.
The freezing weather comes in the wake of a powerful winter storm that dumped snow as far south as Florida.
Meanwhile in Sydney, extreme heat cut power to thousands of people, and charities were handing out water to the homeless.
Play at an international tennis tournament in Sydney had to be postponed when temperatures rose above 40C, while cricketers from England and Australia playing at Sydney Cricket Ground endured the hottest day recorded during a Test match in Australia.
Wildfire warnings are in place for the Sydney area.
#Penrith has just recorded the highest maximum temperature on record the Sydney Metropolitan area with a scorching 47.1 degrees!— NSW Incident Alerts (@nswincidents) January 7, 2018