The sculptures were one of the attractions at the city's two-day Festival of Angels event, which also involved street entertainment and a Christmas market.
However, the plummeting temperatures also wreaked havoc on the region's roads as drivers were faced with black ice and treacherous conditions.
On the A19 near Thirsk there were a series of crashes yesterday morning, the most serious at 8.45am when a Good Samaritan, who had got out of his car to help another motorist – who had hit a lamppost – was hit by a HGV.
The incident took place close to Tim Swales garage on the A19 slip road to the A684, heading towards Northallerton.
The 49-year-old man was taken to James Cook Hospital in Middlesbrough by air ambulance.
Police said the full extent of his injuries was not yet known. The A684 junction was closed following the collision.
Superintendent Aubrey Smith from North Yorkshire Police, said: "Although temperatures are warming up during the daytime, causing the snow and ice to melt, they are still plummeting at night.
"This is causing unpredictable patches of black ice to form on untreated road surfaces.
"I advise all those who involved in collisions to keep as far from the carriageway as possible."