The Ministry of Interior and Safety has raised the country's heat wave risk alert to the second-highest 'orange' on the four-tier scheme as of noon Saturday.

This year's orange alert comes 18 days earlier than last year, which saw the alert issued on July 20.

Heat wave advisories have been issued in 164 of the 178 regions across the country, and some 82 regions will see the heat index, the temperature that people actually feel, surpass 33 degrees Celsius during the day throughout the weekend, due to the humidity.

The country's four-tier heat wave alert consists of blue, yellow, orange and red. 'Orange' is issued when 40 percent of the regions are expected to have at least three consecutive days when people feel the daytime high to be over 33 degrees.

The ministry ordered related ministries and local governments to take measures to protect those vulnerable to heat, including those working outdoors.

An official from the interior ministry called for the public to refrain from outdoor activities and drink a lot of water during a heat wave.