WARSAW, June 27 (Xinhua) -- Poland's Institute of Meteorology and Water Management has issued its highest, third-level heat warnings from Saturday morning to Monday evening.

The peak of the extreme heat event is expected on Sunday, when temperatures in some regions could reach up to 42 degrees Celsius, the weather service said.

Meteorologists said that this heat wave is unlike anything Poland has experienced in over 100 years, with all-time temperature records to be broken in some regions.

Temperatures are expected to gradually ease from Monday in parts of the country. However, the heat will remain intense, with forecasts showing up to 39 degrees Celsius in central Poland. ■