The unusual weather pattern has drastically reduced the depletion of the ozone layer.

The phenomenon has led to the smallest hole on record in the layer over Antarctica, NASA and National Oceanic and Atmospheric Administration (NOAA) satellite data released on Monday said.

The annual ozone hole reached its peak extent of 16. 4 million square kilometers on September 8 and then shrank to less than 10 million square kilometers for the remainder of September and October.

In the typical weather conditions, the ozone hole typically grows to a maximum area of about 20 million square kilometers in late September or early October.

"It's great news for ozone in the Southern Hemisphere," said Paul Newman, chief scientist for Earth Sciences at NASA's Goddard Space Flight Center in Greenbelt, Maryland.

"But it's important to recognize that what we're seeing this year is due to warmer stratospheric temperatures. It's not a sign that atmospheric ozone is suddenly on a fast track to recovery."

The weather systems that disrupted the 2019 ozone hole are typically modest in September, but this year they were unusually strong, dramatically warming the Antarctic's stratosphere during the pivotal time for ozone destruction, NASA statement maintained.

The temperatures during September at an altitude of about 20 kilometers were 16 degrees Celsius warmer than average, warmest weather in the 40-year historical record of the region.

Comprising of three oxygen atoms—O₃—ozone layer acts as a protective shield that prevents dangerous ultraviolet rays from hitting the earth. Sustained exposure to ultraviolet rays causes skin cancer and is also harmful to plants.

Every year, the Antarctic ozone hole typically expands during late winter with sun rays reacting with chlorine and bromine molecules that are released by chlorofluorocarbons (CFCs).

These compounds were used frequently for coolants, including refrigerators and air conditioners.

Concerned over the environmental damage, the Montreal Protocol was signed in 1987, banning the production and use of the compounds that destroy the ozone layer. The action helped in the repair of the ozone layer in the late 1980s.

"This is the third time in the last 40 years that weather systems have caused warm temperatures that limit ozone depletion," said Susan Strahan, an atmospheric scientist with Universities Space Research Association.

"Similar weather patterns in the Antarctic stratosphere in September 1988 and 2002 also produced atypically small ozone holes. It's a rare event that we're still trying to understand," she said.