Early sizzling temperatures that hit the country last month led to record-breaking electricity demand for the month of June, data showed Monday.

According to Korea Power Exchange, the country’s average maximum power demand stood at 71,805 megawatts last month, up 4.3 percent on-year -- the highest since records began in June 2005.

It is also the first year that the average maximum power demand surpassed 70,000 megawatts.

The sudden surge of power consumption resulted from many households and buildings turning up the air conditioning due to the first-ever tropical night for June across the country.

A tropical night is when the temperature does not fall below 25 degrees Celsius between 6 p.m. and 9 a.m.

As power consumption surged, South Korea’s reserve electricity ratio fell below the 10 percent level for the first time this year.

The reserve ratio that should be maintained above 10 percent to supply stable power and prepare for emergencies, is likely to further drop in July and August—months during which power consumption jumps due to air conditioning use, according to industry watchers.

In that case, the government could impose emergency measures for the first time since September 2013 to control power use.

The Ministry of Trade, Industry and Energy forecasts that electricity demand will rise to the 91.7-95.7 gigawatt range in the second week of August when the summer heat usually reaches its peak, up from 91.1 gigawatts measured last year.

The ministry expects power reserves to plunge to their lowest levels in recent years -- to around 5.2 gigawatts this summer, half of that of last year.