South Korea has recorded 22 tropical nights in July—it’s highest since records began in 1908, the weather agency said Thursday, according to Al Jazeera.

A tropical night is when temperatures stay above 25°C overnight. In Seoul, one night didn’t dip below 29.3°C.

The country is facing an intense heat wave, with some areas hitting over 40°C. At least 16 people have died from heat-related illnesses, Al Jazeera reported.

Experts warn such extremes are becoming more common due to climate change.