It's that time of the year again in Shimla when a red balloon is tethered to the roof of the British-era municipal corporation building. It signals the opening of Shimla's ice-skating rink, Asia's oldest.

The temperature dipped on Wednesday night to 4.6 degrees Celsius, following which a thick sheet of naturally-formed ice surfaced in the rink in the morning.

Over 200 skaters, mainly youngsters, enjoyed their run at the rink on Thursday morning. Skaters Rubina Sethi and Nidhi Kashyap said: "We are quite excited about the onset of the skating season, though much delayed. We will definitely enjoy our winter school break."

The rink held 86 sessions during 2010-11 when winter was quite chilly compared to the previous five or six years. In 2009-2010, it hosted 77 skating sessions. But a year earlier, only 27 sessions could be held, the lowest in the rink's history.

The idea of a natural skating rink was developed by an Irish military official named Blessington who lived in Shimla. He had inadvertently kept a bucket of water outside his residence and in the morning found it had frozen. That gave him the idea of a skating rink and he created a small one of his own in 1920.

So that everybody living across the undulating landscape of the town could be told -- in an era without telephones and public address systems -- that the rink was ready and open to skaters, the practice of tethering a red balloon to the roof of the municipality was adopted. It survives till date.

"The skating club holds two sessions a day - in the morning and the evening. The morning session is from 8 a.m. to 11 a.m. while the one in the evening is from 5.30 p.m. to 8 p.m," Bhuvnesh Banga, secretary of the Simla Ice Skating Club, said.