At least a dozen flights to and from Leh, in Ladakh, have been cancelled since Saturday due to unusually high temperatures in the Union Territory, reported The Times of India.

Temperatures in the region climbed to 36 degrees Celsius over the weekend, according to the newspaper.

According to the India Meteorological Department, however, the maximum daytime temperature in Leh was 29.5 degrees Celsius on Thursday. The temperature rose to 32.5 degrees Celsius on Saturday and 33.5 degrees Celsius on Sunday.

Such high temperatures are atypical in Leh, which sits at an altitude of 11,000 feet and where the mercury plummets to as low as -20 degrees Celsius in the winter. Unusually warm temperatures at such high altitudes cause the air to become much thinner than is safe for commercial flight operations.

Leh’s Kushok Bakula Rimpochee Airport is one of the highest in the world.

The Times of India quoted an unidentified official from the Leh airport as saying that this was likely to have been the first time that flights were cancelled there due to high temperatures. “Last year, the temperature was not so high as to affect flights,” the official said.

Leh typically sees 15 to 16 aircraft arrivals and departures each day. On Saturday, two flights were cancelled, followed by four on Sunday and six on Monday.

“High ground temperatures and runway restrictions in Leh have necessitated the cancellation of all flights for today,” the private airline Indigo said in a statement on Monday.

The Himalayan region reeled under a heatwave this month.

In the adjacent Union territory of Jammu and Kashmir, for example, several places recorded their highest July temperature in 25 years on July 28, reported PTI.

Srinagar clocked a maximum daytime temperature of 36.2 degrees Celsius on Sunday, marking its hottest July day since July 9, 1999, when the temperature peaked at 37 degrees Celsius.